Is filename one word

A filename or file name is a name used to uniquely identify a computer file in a file system. Different file systems impose different restrictions on filename lengths.

A filename may (depending on the file system) include:

• name – base name of the file
• extension – may indicate the format of the file (e.g. .txt for plain text, .pdf for Portable Document Format, .dat for unspecified binary data, etc.)

The components required to identify a file by utilities and applications varies across operating systems, as does the syntax and format for a valid filename.

Filenames may contain any arbitrary bytes the user chooses. This may include things like a revision or generation number of the file such as computer code, a numerical sequence number (widely used by digital cameras through the DCF standard), a date and time (widely used by smartphone camera software and for screenshots), and/or a comment such as the name of a subject or a location or any other text to facilitate the searching the files. In fact, even unprintable characters, including bell, 0x00, Return and LineFeed can be part of a filename, although most utilities do not handle them well.

Some people use of the term filename when referring to a complete specification of device, subdirectories and filename such as the Windows C:Program FilesMicrosoft GamesChessChess.exe. The filename in this case is Chess.exe. Some utilities have settings to suppress the extension as with MS Windows Explorer.

History[edit]

On early personal computers using the CP/M operating system, with the File Allocation Table (FAT) filesystem, filenames were always 11 characters. This was referred to as the 8.3 filename with a maximum of an 8 byte name and a maximum of a 3 byte extension. Utilities and applications allowed users to specify filenames without trailing spaces and include a dot before the extension. The dot was not actually stored in the directory. Using only 7 bit characters allowed several file attributes ^[1]to be included in the actual filename by using the high-order-bit. These attributes included Readonly, Archive, HIDDEN and SYS. Eventually this was too restrictive and the number of characters allowed increased. The attribute bits were moved to a special block of the file including additional information. This led to compatibility problems when moving files between different file systems.^[2]

During the 1970s, some mainframe and minicomputers where files on the system were identified by a user name, or account number.

For example, on Digital Equipment Corporation RSTS/E and TOPS-10 operating systems, files were identified by

• optional device name (one or two characters) followed by an optional unit number, and a colon «:». If not present, it was presumed to be SY:
• the account number, consisting of a bracket «[«, a pair of numbers separated by a comma, and followed by a close bracket «]». If omitted, it was presumed to be yours.
• mandatory file name, consisting of 1 to 6 characters (upper-case letters or digits)
• optional 3-character extension.

On the IBM OS/VS1, OS/390 and MVS operating systems, a file name was up to 44 characters, consisting of upper case letters, digits, and the period. A file name must start with a letter or number, a period must occur at least once each 8 characters, two consecutive periods could not appear in the name, and must end with a letter or digit. By convention, the letters and numbers before the first period was the account number of the owner or the project it belonged to, but there was no requirement to use this convention.

On the McGill University MUSIC/SP system, file names consisted of

• Optional account number, which was one to four characters followed by a colon.If the account number was missing, it was presumed to be in your account, but if it was not, it was presumed to be in the *COM: pseudo-account, which is where all files marked as public were catalogued.
• 1-17 character file name, which could be upper case letters or digits, and the period, with the requirement it not begin or end with a period, or have two consecutive periods.

The Univac VS/9 operating system had file names consisting of

• Account name, consisting of a dollar sign «$», a 1-7 character (letter or digit) username, and a period («.»). If not present it was presumed to be in your account, but if it wasn’t, the operating system would look in the system manager’s account $TSOS. If you typed in a dollar sign only as the account, this would indicate the file was in the $TSOS account unless the first 1-7 character of the file name before the first period matched an actual account name, then that account was used, e.g. ABLE.BAKER is a file in your account, but if not there the system would search for $TSOS.ABLE.BAKER, but if $ABLE.BAKER was specified, the file $TSOS.ABLE.BAKER would be used unless $ABLE was a valid account, then it would look for a file named BAKER in that account.
• File name, 1-56 characters (letters and digits) separated by periods. File names cannot start or end with a period, nor can two consecutive periods appear.

In 1985, RFC 959 officially defined a pathname to be the character string that must be entered into a file system by a user in order to identify a file.^[3]

Around 1995, VFAT, an extension to the MS-DOS FAT filesystem, was introduced in Windows 95 and Windows NT. It allowed mixed-case Unicode long filenames (LFNs), in addition to classic «8.3» names.

References: absolute vs relative[edit]

An absolute reference includes all directory levels. In some systems, a filename reference that does not include the complete directory path defaults to the current working directory. This is a relative reference. One advantage of using a relative reference in program configuration files or scripts is that different instances of the script or program can use different files.

This makes an absolute or relative path composed of a sequence of filenames.

Number of names per file[edit]

Unix-like file systems allow a file to have more than one name; in traditional Unix-style file systems, the names are hard links to the file’s inode or equivalent. Windows supports hard links on NTFS file systems, and provides the command fsutil in Windows XP, and mklink in later versions, for creating them.^[4][5] Hard links are different from Windows shortcuts, classic Mac OS/macOS aliases, or symbolic links. The introduction of LFNs with VFAT allowed filename aliases. For example, longfi~1.??? with a maximum of eight plus three characters was a filename alias of «long file name.???» as a way to conform to 8.3 limitations for older programs.

This property was used by the move command algorithm that first creates a second filename and then only removes the first filename.

Other filesystems, by design, provide only one filename per file, which guarantees that alteration of one filename’s file does not alter the other filename’s file.

Length restrictions[edit]

Some filesystems restrict the length of filenames. In some cases, these lengths apply to the entire file name, as in 44 characters on IBM S/370.^[6] In other cases, the length limits may apply to particular portions of the filename, such as the name of a file in a directory, or a directory name. For example, 9 (e.g., 8-bit FAT in Standalone Disk BASIC), 11 (e.g. FAT12, FAT16, FAT32 in DOS), 14 (e.g. early Unix), 21 (Human68K), 31, 30 (e.g. Apple DOS 3.2 and 3.3), 15 (e.g. Apple ProDOS), 44 (e.g. IBM S/370),^[6] or 255 (e.g. early Berkeley Unix) characters or bytes. Length limits often result from assigning fixed space in a filesystem to storing components of names, so increasing limits often requires an incompatible change, as well as reserving more space.

A particular issue with filesystems that store information in nested directories is that it may be possible to create a file with a complete pathname that exceeds implementation limits, since length checking may apply only to individual parts of the name rather than the entire name. Many Windows applications are limited to a MAX_PATH value of 260, but Windows file names can easily exceed this limit [1]. From Windows 10, version 1607, MAX_PATH limitations have been removed.^[7]

Filename extensions[edit]

Many file systems, including FAT, NTFS, and VMS systems, consider as filename extension the part of the file name that consists of one or more characters following the last period in the filename, dividing the filename into two parts: a base name or stem and an extension or suffix used by some applications to indicate the file type. Multiple output files created by an application use the same basename and various extensions. For example, a compiler might use the extension FOR for source input file (for Fortran code), OBJ for the object output and LST for the listing. Although there are some common extensions, they are arbitrary and a different application might use REL and RPT. Extensions have been restricted, at least historically on some systems, to a length of 3 characters, but in general can have any length, e.g., html.

Encoding interoperability[edit]

There is no general encoding standard for filenames.

File names have to be exchanged between software environments for network file transfer, file system storage, backup and file synchronization software, configuration management, data compression and archiving, etc. It is thus very important not to lose file name information between applications. This led to wide adoption of Unicode as a standard for encoding file names, although legacy software might not be Unicode-aware.

Encoding indication interoperability[edit]

Traditionally, filenames allowed any character in their filenames as long as they were file system safe.^[2] Although this permitted the use of any encoding, and thus allowed the representation of any local text on any local system, it caused many interoperability issues.

A filename could be stored using different byte strings in distinct systems within a single country, such as if one used Japanese Shift JIS encoding and another Japanese EUC encoding. Conversion was not possible as most systems did not expose a description of the encoding used for a filename as part of the extended file information. This forced costly filename encoding guessing with each file access.^[2]

A solution was to adopt Unicode as the encoding for filenames.

In the classic Mac OS, however, encoding of the filename was stored with the filename attributes.^[2]

Unicode interoperability[edit]

The Unicode standard solves the encoding determination issue.

Nonetheless, some limited interoperability issues remain, such as normalization (equivalence), or the Unicode version in use. For instance, UDF is limited to Unicode 2.0; macOS’s HFS+ file system applies NFD Unicode normalization and is optionally case-sensitive (case-insensitive by default.) Filename maximum length is not standard and might depend on the code unit size. Although it is a serious issue, in most cases this is a limited one.^[2]

On Linux, this means the filename is not enough to open a file: additionally, the exact byte representation of the filename on the storage device is needed. This can be solved at the application level, with some tricky normalization calls.^[8]

The issue of Unicode equivalence is known as «normalized-name collision». A solution is the Non-normalizing Unicode Composition Awareness used in the Subversion and Apache technical communities.^[9] This solution does not normalize paths in the repository. Paths are only normalized for the purpose of comparisons. Nonetheless, some communities have patented this strategy, forbidding its use by other communities.^{[clarification needed]}

Perspectives[edit]

To limit interoperability issues, some ideas described by Sun are to:

• use one Unicode encoding (such as UTF-8)
• do transparent code conversions on filenames
• store no normalized filenames
• check for canonical equivalence among filenames, to avoid two canonically equivalent filenames in the same directory.^[2]

Those considerations create a limitation not allowing a switch to a future encoding different from UTF-8.

Unicode migration[edit]

One issue was migration to Unicode.
For this purpose, several software companies provided software for migrating filenames to the new Unicode encoding.

• Microsoft provided migration transparent for the user throughout the VFAT technology
• Apple provided «File Name Encoding Repair Utility v1.0».^[10]
• The Linux community provided “convmv”.^[11]

Mac OS X 10.3 marked Apple’s adoption of Unicode 3.2 character decomposition, superseding the Unicode 2.1 decomposition used previously. This change caused problems for developers writing software for Mac OS X.^[12]

Uniqueness[edit]

Within a single directory, filenames must be unique. Since the filename syntax also applies for directories, it is not possible to create a file and directory entries with the same name in a single directory. Multiple files in different directories may have the same name.

Uniqueness approach may differ both on the case sensitivity and on the Unicode normalization form such as NFC, NFD.
This means two separate files might be created with the same text filename and a different byte implementation of the filename, such as L»x00C0.txt» (UTF-16, NFC) (Latin capital A with grave) and L»x0041x0300.txt» (UTF-16, NFD) (Latin capital A, grave combining).^[13]

Letter case preservation[edit]

Some filesystems, such as FAT, store filenames as upper-case regardless of the letter case used to create them. For example, a file created with the name «MyName.Txt» or «myname.txt» would be stored with the filename «MYNAME.TXT». Any variation of upper and lower case can be used to refer to the same file. These kinds of file systems are called case-insensitive and are not case-preserving. Some filesystems prohibit the use of lower case letters in filenames altogether.

Some file systems store filenames in the form that they were originally created; these are referred to as case-retentive or case-preserving. Such a file system can be case-sensitive or case-insensitive. If case-sensitive, then «MyName.Txt» and «myname.txt» may refer to two different files in the same directory, and each file must be referenced by the exact capitalization by which it is named. On a case-insensitive, case-preserving file system, on the other hand, only one of «MyName.Txt», «myname.txt» and «Myname.TXT» can be the name of a file in a given directory at a given time, and a file with one of these names can be referenced by any capitalization of the name.

From its original inception, Unix and its derivative systems were case-preserving. However, not all Unix-like file systems are case-sensitive; by default, HFS+ in macOS is case-insensitive, and SMB servers usually provide case-insensitive behavior (even when the underlying file system is case-sensitive, e.g. Samba on most Unix-like systems), and SMB client file systems provide case-insensitive behavior. File system case sensitivity is a considerable challenge for software such as Samba and Wine, which must interoperate efficiently with both systems that treat uppercase and lowercase files as different and with systems that treat them the same.^[14]

Reserved characters and words[edit]

File systems have not always provided the same character set for composing a filename. Before Unicode became a de facto standard, file systems mostly used a locale-dependent character set. By contrast, some new systems permit a filename to be composed of almost any character of the Unicode repertoire, and even some non-Unicode byte sequences. Limitations may be imposed by the file system, operating system, application, or requirements for interoperability with other systems.

Many file system utilities prohibit control characters from appearing in filenames. In Unix-like file systems, the null character^[15] and the path separator / are prohibited.

In Windows[edit]

File system utilities and naming conventions on various systems prohibit particular characters from appearing in filenames or make them problematic:^[16]

Character	Name	Reason for prohibition
/	slash	Used as a path name component separator in Unix-like, Windows, and Amiga systems. (For as long as the SwitChar setting is set to ‘/ ’, the DOS COMMAND.COM shell would consume it as a switch character, but DOS and Windows themselves always accept it as a separator on API level.) The big solidus ⧸ (Unicode code point U+29F8) is permitted in Windows filenames.
	backslash	Used as the default path name component separator in DOS, OS/2 and Windows (even if the SwitChar is set to ‘-‘; allowed in Unix filenames, see Note 1). The big reverse solidus ⧹ (U+29F9) is permitted in Windows filenames.
?	question mark	Used as a wildcard in Unix, Windows and AmigaOS; marks a single character. Allowed in Unix filenames, see Note 1. The glottal stop ʔ (U+0294), the interrobang ‽ (U+203D), the inverted question mark ¿ (U+00BF) and the double question mark ⁇ (U+2047) are allowed in all filenames.
%	percent	Used as a wildcard in RT-11; marks a single character. Not special on Windows.
*	asterisk or star	Used as a wildcard in Unix, DOS, RT-11, VMS and Windows. Marks any sequence of characters (Unix, Windows, DOS) or any sequence of characters in either the basename or extension (thus «*.*» in DOS means «all files». Allowed in Unix filenames, see Note 1. See Star (glyph) for many asterisk-like characters allowed in filenames.
:	colon	Used to determine the mount point / drive on Windows; used to determine the virtual device or physical device such as a drive on AmigaOS, RT-11 and VMS; used as a pathname separator in classic Mac OS. Doubled after a name on VMS, indicates the DECnet nodename (equivalent to a NetBIOS (Windows networking) hostname preceded by «\».). Colon is also used in Windows to separate an alternative data stream from the main file. The letter colon ꞉ (U+A789) and the ratio symbol ∶ (U+2236) are permitted in Windows filenames. In the Segoe UI font, used in Windows Explorer, the glyphs for the colon and the letter colon are identical.
|	vertical bar or pipe	Designates software pipelining in Unix, DOS and Windows; allowed in Unix filenames, see Note 1. The mathematical operator ∣ (U+2223) is permitted in Windows filenames.
"	straight double quote	A legacy restriction carried over from DOS. The single quotes ‘ (U+0027), ‘ (U+2018), and ’ (U+2019) and the curved double quotes “ (U+201C) and ” (U+201D) are permitted anywhere in filenames. See Note 1.
<	less than	Used to redirect input, allowed in Unix filenames, see Note 1. The spacing modifier letter ˂ (U+2C2) is permitted in Windows filenames.
>	greater than	Used to redirect output, allowed in Unix filenames, see Note 1. The spacing modifier letter ˃ (U+2C3) is permitted in Windows filenames.
.	period or dot	Folder names cannot end with a period in Windows, though the name can end with a period followed by a whitespace character such as a non-breaking space. Elsewhere, the period is allowed, but the last occurrence will be interpreted to be the extension separator in VMS, DOS, and Windows. In other OSes, usually considered as part of the filename, and more than one period (full stop) may be allowed. In Unix, a leading period means the file or folder is normally hidden.
,	comma	Allowed, but treated as separator by the command line interpreters COMMAND.COM and CMD.EXE on DOS and Windows.
;	semicolon	Allowed, but treated as separator by the command line interpreters COMMAND.COM and CMD.EXE on DOS and Windows.
=	equals sign	Allowed, but treated as separator by the command line interpreters COMMAND.COM and CMD.EXE on DOS and Windows.
	space	Allowed, but the space is also used as a parameter separator in command line applications. This can be solved by quoting the entire filename.

Note 1: While they are allowed in Unix file and folder names, most Unix shells require specific characters such as spaces, <, >, |, , and sometimes :, (, ), &, ;, #, as well as wildcards such as ? and *, to be quoted or escaped:

five and six<seven (example of escaping)
'five and six<seven' or "five and six<seven" (examples of quoting)

The character å (0xE5) was not allowed as the first letter in a filename under 86-DOS and MS-DOS/PC DOS 1.x-2.x, but can be used in later versions.

In Windows utilities, the space and the period are not allowed as the final character of a filename.^[17] The period is allowed as the first character, but some Windows applications, such as Windows Explorer, forbid creating or renaming such files (despite this convention being used in Unix-like systems to describe hidden files and directories). Workarounds include appending a dot when renaming the file (that is then automatically removed afterwards), using alternative file managers, creating the file using the command line, or saving a file with the desired filename from within an application.^[18]

Some file systems on a given operating system (especially file systems originally implemented on other operating systems), and particular applications on that operating system, may apply further restrictions and interpretations. See comparison of file systems for more details on restrictions.

In Unix-like systems, DOS, and Windows, the filenames «.» and «..» have special meanings (current and parent directory respectively). Windows 95/98/ME also uses names like «…», «….» and so on to denote grandparent or great-grandparent directories.^[19] All Windows versions forbid creation of filenames that consist of only dots, although names consist of three dots («…») or more are legal in Unix.

In addition, in Windows and DOS utilities, some words are also reserved and cannot be used as filenames.^[18] For example, DOS device files:^[20]

CON, CONIN$, CONOUT$, PRN, AUX, CLOCK$, NUL
COM0, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9[21]
LPT0, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, LPT9[21]
LST (only in 86-DOS and DOS 1.xx)
KEYBD$, SCREEN$ (only in multitasking MS-DOS 4.0)
$IDLE$ (only in Concurrent DOS 386, Multiuser DOS and DR DOS 5.0 and higher)
CONFIG$ (only in MS-DOS 7.0-8.0)

Systems that have these restrictions cause incompatibilities with some other filesystems. For example, Windows will fail to handle, or raise error reports for, these legal UNIX filenames: aux.c,^[22] q»uote»s.txt, or NUL.txt.

NTFS filenames that are used internally include:

$Mft, $MftMirr, $LogFile, $Volume, $AttrDef, $Bitmap, $Boot, $BadClus, $Secure,
$Upcase, $Extend, $Quota, $ObjId and $Reparse

Comparison of filename limitations[edit]

System	Case sensitive	Case preserving	Allowed character set	Reserved characters	Reserved words	Maximum length (characters)	Comments
8-bit FAT	?	?	7-bit ASCII (but stored as bytes)	first character not allowed to be 0x00 or 0xFF		9	Maximum 9 character base name limit for sequential files (without extension), or maximum 6 and 3 character extension for binary files; see 6.3 filename
FAT12, FAT16, FAT32	No	No	any SBCS/DBCS OEM codepage	0x00-0x1F 0x7F " * / : < > ? | + , . ; = [ ] (in some environments also: ! @; DOS 1/2 did not allow 0xE5 as first character)	Device names including: $IDLE$ AUX COM1…COM4 CON CONFIG$ CLOCK$ KEYBD$ LPT1…LPT4 LST NUL PRN SCREEN$ (depending on AVAILDEV status everywhere or only in virtual DEV directory)	11	Maximum 8 character base name limit and 3 character extension; see 8.3 filename
VFAT	No	Yes	Unicode, using UCS-2 encoding	0x00-0x1F 0x7F " * / : < > ? |		255
exFAT	No	Yes	Unicode, using UTF-16 encoding	0x00-0x1F 0x7F " * / : < > ? |		255
NTFS	Optional	Yes	Unicode, using UTF-16 encoding	0x00-0x1F 0x7F " * / : < > ? |	Only in root directory: $AttrDef $BadClus $Bitmap $Boot $LogFile $MFT $MFTMirr pagefile.sys $Secure $UpCase $Volume $Extend $Extend$ObjId $Extend$Quota $Extend$Reparse ($Extend is a directory)	255	Paths can be up to 32,000 characters. Forbids the use of characters in range 1-31 (0x01-0x1F) and characters » * / : < > ? | unless the name is flagged as being in the Posix namespace. NTFS allows each path component (directory or filename) to be 255 characters long[dubious – discuss]. Windows forbids the use of the MS-DOS device names AUX, CLOCK$, COM0, …, COM9, CON, LPT0, …, LPT9, NUL and PRN, as well as these names with any extension (for example, AUX.txt), except when using Long UNC paths (ex. \.C:nul.txt or \?D:auxcon). (CLOCK$ may be used, if an extension is provided.) The Win32 API strips trailing period (full-stop), and leading and trailing space characters from filenames, except when UNC paths are used. These restrictions only apply to Windows; in Linux distributions that support NTFS, filenames are written using NTFS’s Posix namespace, which allows any Unicode character except / and NUL.
OS/2 HPFS	No	Yes	any 8-bit set	|?*<«:>/		254
Mac OS HFS	No	Yes	any 8-bit set	:		255	old versions of Finder are limited to 31 characters
Mac OS HFS+	Optional	Yes	Unicode, using UTF-16 encoding	: on disk, in classic Mac OS, and at the Carbon layer in macOS; / at the Unix layer in macOS		255	Mac OS 8.1 — macOS
macOS APFS	Optional	Yes	Unicode, using UTF-16 encoding[citation needed]	In the Finder, filenames containing / can be created, but / is stored as a colon (:) in the filesystem, and is shown as such on the command line. Filenames containing : created from the command line are shown with / instead of : in the Finder, so that it is impossible to create a file that the Finder shows as having a : in its filename.		255	macOS[clarification needed]
most UNIX file systems	Yes	Yes	any 8-bit set	/ null		255	a leading . indicates that ls and file managers will not show the file by default
z/OS classic MVS filesystem (datasets)	No	No	EBCDIC code pages	other than $ # @ — x’C0′		44	first character must be alphabetic or national ($, #, @) «Qualified» contains . after every 8 characters or fewer.[23] Partitioned data sets (PDS or PDSE) are divided into members with names of up to 8 characters; the member name is placed in parenthesises after the name of the PDS, e.g. PAYROLL.DEV.CBL(PROG001)
CMS file system	No	No	EBCDIC code pages			8 + 8	Single-level directory structure with disk letters (A–Z). Maximum of 8 character file name with maximum 8 character file type, separated by whitespace. For example, a TEXT file called MEMO on disk A would be accessed as «MEMO TEXT A». (Later versions of VM introduced hierarchical filesystem structures, SFS and BFS, but the original flat directory «minidisk» structure is still widely used.)
early UNIX (AT&T Corporation)	Yes	Yes	any 8-bit set	/		14	a leading . indicates a «hidden» file
POSIX «Fully portable filenames»[24]	Yes	Yes	A–Z a–z 0–9 . _ -	/ null		14	hyphen must not be first character. A command line utility checking for conformance, «pathchk», is part of the IEEE 1003.1 standard and of The Open Group Base Specifications[25]
ISO 9660	No	?	A–Z 0–9 _ .			«close to 180″(Level 2) or 200(Level 3)	Used on CDs; 8 directory levels max (for Level 1, not level 2,3)
Amiga OFS	No	Yes	any 8-bit set	: / null		30	Original File System 1985
Amiga FFS	No	Yes	any 8-bit set	: / null		30	Fast File System 1988
Amiga PFS	No	Yes	any 8-bit set	: / null		107	Professional File System 1993
Amiga SFS	No	Yes	any 8-bit set	: / null		107	Smart File System 1998
Amiga FFS2	No	Yes	any 8-bit set	: / null		107	Fast File System 2 2002
BeOS BFS	Yes	Yes	Unicode, using UTF-8 encoding	/		255
DEC PDP-11 RT-11	No	No	RADIX-50			6 + 3	Flat filesystem with no subdirs. A full «file specification» includes device, filename and extension (file type) in the format: dev:filnam.ext.
DEC VAX VMS	No	From v7.2	A–Z 0–9 $ - _			32 per component; earlier 9 per component; latterly, 255 for a filename and 32 for an extension.	a full «file specification» includes nodename, diskname, directory/ies, filename, extension and version in the format: OURNODE::MYDISK:[THISDIR.THATDIR]FILENAME.EXTENSION;2 Directories can only go 8 levels deep.
Commodore DOS	Yes	Yes	any 8-bit set	:, =	$	16	length depends on the drive, usually 16
HP 250	Yes	Yes	any 8-bit set	SPACE ", : NULL CHR$(255)		6	Disks and tape drives are addressed either using a label (up to 8 characters) or a unit specification. The HP 250 file system does not use directories, nor does it use extensions to indicate file type. Instead the type is an attribute (e.g. DATA, PROG, BKUP or SYST for data files, program files, backups and the OS itself).[26]

See also[edit]

• File system
• Fully qualified file name
• Long filename
• Path (computing)
• Slug (Web publishing)
• Symbolic link
• Uniform Resource Identifier (URI)
• Uniform Resource Locator (URL) and Internationalized resource identifier
• Windows (Win32) File Naming Conventions (Filesystem Agnostic)

References[edit]

External links[edit]

• Data Formats Filename at Curlie
• File Extension Library
• File Extension Database
• FILExt
• WikiExt — File Extensions Encyclopedia
• Naming Files, Paths, and Namespaces (MSDN)
• 2009 POSIX portable filename character set
• Standard ECMA-208, December 1994, System-Independent Data Format
• Best Practices for File Naming, USA: Stanford University Libraries, Data Management Services

Your question title says «files containing» a word. However, in your question, you do mention «get the filenames containing» a word. These are different things. Fortunately, they are both rather simple, so I will simply show you both.

To find files containing a word:

grep -iR «word1» .

The -i says to ignore case. The -R is recursive (meaning sub-directories are searched). (Capital letter is documented by OpenBSD and more similar to ls, so I prefer that over -r.) The period specifies where to start looking.

To find filenames containing a word:

find . -iname «word1«

The -iname is a case-insensitive version of «name».

The period specifies where to start looking. The current directory is often a good choice.

Note: You referenced «.» in one of your examples. That was great for DOS, and typically good in Microsoft Windows, but is a really bad habit for Unix environment. Seeing that makes me think you’re familiar with Windows. Well, understand that in Windows, «FIND» (or «find») locates text in files. Unix is different: «grep» locates text in files, and «find» locates filenames.

Now, to exclude word 99, and to place that in a text file, add the following text:

| grep -v word99 >> output.txt

This is the pipe key, almost always Shift-Backslash.

So, as an example, if you wanted to do both, use:

grep -iR «word1» . | grep -v word99 >> output.txt
find . -iname «word1» | grep -v word99 >> output.txt

The part before the pipe character will run a command, and send the output into a Unix-style pipe. Then, the content gets sent from the pipe into the next command’s standard input. grep -v will look at the standard input it receives, and exclude what you want. grep -v will send the remaining results to its standard output. The >> will redirect the prior command’s standard output to the end of the specified text file.

The reason why you don’t see documented options in the «find» command, about how to exclude text, is that Unix was very heavily designed with this idea of making simpler programs, and using the piping technique to cause elaborate effects. In the Microsoft environments, old Microsoft code was particularly more cumbersome with pipe-handling, so programs basically tried to incorporate more functionality into each program. On one hand, that seems simpler for the end user (having everything built-in), but that approach lacks consistency. When you’re using Unix, don’t be afraid of the piping: once you get used to it, you may find it simplifies things greatly, but cause you can use your simple tools in many situations, and so you don’t need to re-learn simple techniques over and over (for each different program).

1, Naming conventions

Naming conventions commonly used in the market:

• Camel case (small hump nomenclature – initial lowercase)
• PascalCase (hump nomenclature – initial capital)
• Kebab case
• Snake (underlined)

1.1 naming of project documents

Rules can be quickly remembered as «static file underline, compiled file dashes».

1.1.1 project name

All in lowercase, separated by dashes. Example: my project name

1.1.2 directory name

Refer to the project naming rules. If there is a plural structure, the plural naming method shall be adopted. Examples: docs, assets, components, directives, mixins, utils, views

my-project-name/
|- BuildScript    // Pipeline deployment file directory
|- docs           // Detailed document directory for the project (optional)
|- nginx          // Front end project nginx agent file directory deployed on container
|- node_modules   // Downloaded dependent packages
|- public         // Static page directory
    |- index.html // Project entrance
|- src            // Source directory
    |- api        // http request directory
    |- assets     // Static resource directory, where the resources will be built by wabpack
        |- icon   // icon storage directory
        |- img    // Picture storage directory
        |- js     // Public js file directory
        |- scss   // Public style scss storage directory
            |- frame.scss   // Entry file
            |- global.scss  // Common style
            |- reset.scss   // reset styles 
    |- components     // assembly
    |- plugins        // plug-in unit
    |- router         // route
    |- routes         // Detailed route splitting directory (optional)
        |- index.js
    |- store          // Global state management
    |- utils          // Tool storage directory
        |- request.js // Public request tool
    |- views          // Page storage directory
    |- App.vue        // Root component
    |- main.js        // Entry file
    |- tests          // test case
    |- .browserslistrc// Browser compatibility profile
    |- .editorconfig  // Editor profile
    |- .eslintignore  // eslint ignore rule
    |- .eslintrc.js   // eslint rule
    |- .gitignore     // git ignore rule
    |- babel.config.js // babel rule
    |- Dockerfile // Docker deployment file
    |- jest.config.js
    |- package-lock.json
    |- package.json // rely on
    |- README.md // Project README
    |- vue.config.js // webpack configuration

1.1.3 image file name

All are in lowercase. Single word naming is preferred, and multiple word names are separated by underline.

banner_sina.gif
menu_aboutus.gif
menutitle_news.gif
logo_police.gif
logo_national.gif
pic_people.jpg
pic_TV.jpg

1.1.4 HTML file name

All are in lowercase. Single word naming is preferred, and multiple word names are separated by underline.

|- error_report.html
|- success_report.html

1.1.5 CSS file name

All are in lowercase. Single word naming is preferred, and multiple word names are separated by a dash.

|- normalize.less
|- base.less
|- date-picker.scss
|- input-number.scss

1.1.6 JavaScript file name

All are in lowercase. Single word naming is preferred, and multiple word names are separated by a dash.

|- index.js
|- plugin.js
|- util.js
|- date-util.js
|- account-model.js
|- collapse-transition.js

The above rules can be quickly remembered as «static file underline, compiled file dashes».

1.2 Vue component naming

1.2.1 single file component name

Single file components with a file extension of. vue. Single file component names should always start with uppercase words (PascalCase).

components/
|- MyComponent.vue

1.2.2 single instance component name

Components with only a single active instance should be named with The prefix to show their uniqueness.

This does not mean that the component can only be used for a single page, but_ Each page_ Use only once. These components will never accept any props because they are customized for your application. If you find it necessary to add prop, it indicates that it is actually a reusable component_ Just now_ Use only once per page.

For example, the header and sidebar components are used in almost every page and do not accept prop. This component is specially customized for the application.

components/
|- TheHeading.vue
|- TheSidebar.vue

1.2.3 basic component name

Basic components: basic components that do not contain business, independent and specific functions, such as date selector, modal box, etc. As the basic control of the project, such components will be widely used. Therefore, the API of components is abstracted too much, and different functions can be realized through different configurations.

The basic components that apply specific styles and conventions (that is, the components that display classes, are illogical or stateless, and are not doped with business logic) should all begin with a specific prefix — Base.

Basic components can be used multiple times in one page and can be reused in different pages. They are highly reusable components.

components/
|- BaseButton.vue
|- BaseTable.vue
|- BaseIcon.vue

1.2.4 business components

Business component: unlike the basic component, which only contains a function, it is reused by multiple pages in the business (with reusability). The difference between it and the basic component is that the business component will only be used in the current project, not universal, and will contain some businesses, such as data requests; The basic component contains no business and can be used in any project. It has a single function, such as an input box with data verification function.

Components doped with complex business (with their own data and prop related processing) that is, business components should be named with the prefix Custom.

A business component is in a page. For example, there is a card list in a page, and the card whose style and logic are closely related to the business is a business component.

components/
|- CustomCard.vue

1.2.5 tightly coupled component name

Child components closely coupled with the parent component should be named with the parent component name as a prefix.
Because editors usually organize files alphabetically, this can put the associated files together.

components/
|- TodoList.vue
|- TodoListItem.vue
|- TodoListItemButton.vue

1.2.6 word order in component name

Component names should start with high-level (usually general) words and end with descriptive modifiers.

Because editors usually organize files alphabetically, the important relationships between components are now clear. The following components are mainly used for search and setting functions.

components/
|- SearchButtonClear.vue
|- SearchButtonRun.vue
|- SearchInputQuery.vue
|- SearchInputExcludeGlob.vue
|- SettingsCheckboxTerms.vue
|- SettingsCheckboxLaunchOnStartup.vue

There is another multi-level directory method. Put all search components in the «search» directory and all setting components in the «settings» directory. We only recommend doing this in very large applications (such as 100 + components), because it takes more effort to find between multi-level directories than to scroll through a single component directory.

1.2.7 component name of complete word

Component names should tend to be complete words rather than abbreviations.

Automatic completion in the editor has made the cost of writing long names very low, but the clarity it brings is very valuable. In particular, infrequently used abbreviations should be avoided.

components/
|- StudentDashboardSettings.vue
|- UserProfileOptions.vue

1.3 code parameter naming

1.3.1 name

The component name should always be multiple words and should always be PascalCase. Except for the root component and Vue built-in components such as App and. This avoids conflicts with existing and future HTML elements, because all HTML element names are single words.

export default {
  name: 'ToDoList',
  // ...
}

1.3.2 prop

When declaring prop, its name should always use camelCase, while kebab case should always be used in templates and JSX.

We simply follow the conventions of each language. In JavaScript, camelCase is more natural. In HTML, it is kebab case.

<WelcomeMessage greeting-text="hi"/>

export default {
  name: 'MyComponent',
  // ...
  props: {
    greetingText: {
      type: String,
      required: true,
      validator: function (value) {
        return ['syncing', 'synced',].indexOf(value) !== -1
      }
    }
  }
}

1.3.3 router

Vue Router Path is named in kebab case format. Words using Snake (such as: / user_info) or camelCase (such as: / userInfo) will be regarded as a word, and search engines cannot distinguish semantics.

// bad
{
  path: '/user_info', // user_info as a word
  name: 'UserInfo',
  component: UserInfo,
  meta: {
    title: ' - user',
    desc: ''
  }
},

// good
{
  path: '/user-info', // Can be parsed into user info
  name: 'UserInfo',
  component: UserInfo,
  meta: {
    title: ' - user',
    desc: ''
  }
},

1.3.4 components in formwork

For most projects, the component name should always be Pascal case in single file components and string templates, but always kebab case in DOM templates.

<!-- In single file components and string templates --> 
<MyComponent/>

<!-- stay DOM In template --> 
<my-component></my-component>

1.3.5 self closing assembly

Components without content in single file components, string templates, and JSX should be self closing — but never in DOM templates.

<!-- In single file components and string templates -->
<MyComponent/>

<!-- Everywhere -->
<my-component></my-component>

1.3.6 variables

• Naming method: camelCase
• Naming convention: type + method of object description or attribute

// bad
var getTitle = "LoginTable"

// good
let tableTitle = "LoginTable"
let mySchool = "My school"

1.3.7 constants

• Naming method: all uppercase underline split
• Naming convention: use capital letters and underscores to combine names, and underscores are used to divide words

const MAX_COUNT = 10
const URL = 'http://test.host.com'

1.3.8 method

• Naming method: camelCase
• Naming standard: use verb or verb + noun form uniformly

// 1. In general, use the verb + noun form
// bad
go,nextPage,show,open,login

// good
jumpPage,openCarInfoDialog

// 2. Request data method, ending with data
// bad
takeData,confirmData,getList,postForm

// good
getListData,postFormData

// 3. Single verb situation
init,refresh

verb	meaning	Return value
can	Determine whether an action can be performed (right)	Function returns a Boolean value. true: executable; false: not executable
has	Determine whether there is a value	Function returns a Boolean value. true: contains this value; false: does not contain this value;
is	Determine whether it is a value	Function returns a Boolean value. true: a value; false: not a value;
get	Get a value	Function returns a non Boolean value
set	Set a value	No return value, setting success or chained object

1.3.9 user defined events

Custom events should always use the event name of kebab case.

Unlike components and prop s, there is no automatic case conversion for event names. Instead, the triggered event name needs to exactly match the name used to listen to this event.

this.$emit('my-event')

<MyComponent @my-event="handleDoSomething" />

Unlike components and props, event names are not used as JavaScript variable names or property names, so there is no reason to use camelCase or PascalCase. In addition, the v-on event listener will be automatically converted to all lowercase in the DOM template (because HTML is case insensitive), so v-on:myevent will become v-on:myevent — making it impossible for myEvent to be monitored.

• Native event reference list [1]
  It can be found from the native event that its usage is as follows:

<div
  @blur="toggleHeaderFocus"
  @focus="toggleHeaderFocus"
  @click="toggleMenu"
  @keydown.esc="handleKeydown"
  @keydown.enter="handleKeydown"
  @keydown.up.prevent="handleKeydown"
  @keydown.down.prevent="handleKeydown"
  @keydown.tab="handleKeydown"
  @keydown.delete="handleKeydown"
  @mouseenter="hasMouseHoverHead = true"
  @mouseleave="hasMouseHoverHead = false">
</div>

And to distinguish_ Native event_ And_ Custom event_ For the use in Vue, it is suggested that in addition to using kebab case for multi word event names, the naming should also follow the form of on + verb, as follows:

<!-- Parent component -->
<div
  @on-search="handleSearch"
  @on-clear="handleClear"
  @on-clickoutside="handleClickOutside">
</div>

// Subcomponents
export default {
  methods: {
    handleTriggerItem () {
      this.$emit('on-clear')
    }
  }
}

1.3.10 event method

Naming method: camelCase
Naming convention: handle + name (optional) + verb

<template>
  <div
    @click.native.stop="handleItemClick()"
    @mouseenter.native.stop="handleItemHover()">
  </div>
</template>

<script>

export default {
  methods: {
    handleItemClick () {
      //...
    },
    handleItemHover () {
      //...
    }
  }
}
</script>

2, Code specification

2.1 Vue

2.1.1 code structure

<template>
  <div id="my-component">
    <DemoComponent />
  </div>
</template>

<script>
import DemoComponent from '../components/DemoComponent'

export default {
  name: 'MyComponent',
  components: {
    DemoComponent
  },
  mixins: [],
  props: {},
  data () {
    return {}
  },
  computed: {},
  watch: {}
  created () {},
  mounted () {},
  destroyed () {},
  methods: {},
}
</script>

<style lang="scss" scoped>
#my-component {
}
</style>

2.1.2 data

The data of the component must be a function.

// In a .vue file
export default {
  data () {
    return {
      foo: 'bar'
    }
  }
}

2.1.3 prop

Prop definitions should be as detailed as possible.

export default {
  props: {
    status: {
      type: String,
      required: true,
      validator: function (value) {
        return [
          'syncing', 
          'synced',
          'version-conflict',
          'error'
        ].indexOf(value) !== -1
      }
    }
  }
}

2.1.4 computed

Complex computational attributes should be divided into as many simpler attributes as possible.

Small, focused computing attributes reduce the hypothetical restrictions on the use of information, so there is no need for so much refactoring when requirements change.

// bad
computed: { 
  price: function () { 
    var basePrice = this.manufactureCost / (1 - this.profitMargin) 
    return ( 
      basePrice - 
      basePrice * (this.discountPercent || 0) 
    ) 
  } 
}

// good
computed: {
  basePrice: function () {
    return this.manufactureCost / (1 - this.profitMargin)
  },
  discount: function () {
    return this.basePrice * (this.discountPercent || 0)
  },
  finalPrice: function () {
    return this.basePrice - this.discount
  }
}

2.1.5 setting key values for v-for

key must be used with v-for on components to maintain the state of internal components and their subtrees. Even maintain predictable behavior on elements, such as object constancy in animation [2].

<ul>
  <li
    v-for="todo in todos"
    :key="todo.id">
      {{ todo.text }}
  </li>
</ul>

2.1.6 v-if and v-for are mutually exclusive

Never use v-if and v-for on the same element at the same time.

<!-- bad: Console error -->
<ul>
  <li
    v-for="user in users"
    v-if="shouldShowUsers"
    :key="user.id">
      {{ user.name }}
  </li>
</ul>

We tend to do this in two common situations:

• To filter items in a list (such as v-for = «user in users» v-if = «user.isActive»). In this case, replace users with a calculated attribute (such as activeUsers) to return the filtered list.

computed: {
  activeUsers: function () {
    return this.users.filter((user) => {
      return user.isActive
    })
  }
}

<ul>
  <li
    v-for="user in activeUsers"
    :key="user.id">
      {{ user.name }}
  </li>
</ul>

• To avoid rendering lists that should have been hidden (such as v-for = «user in users» v-if = «shouldShowUsers»). In this case, move the v-if to the container element (such as ul, ol).

<!-- bad -->
<ul>
  <li
    v-for="user in users"
    v-if="shouldShowUsers"
    :key="user.id">
      {{ user.name }}
  </li>
</ul>

<!-- good -->
<ul v-if="shouldShowUsers">
  <li
    v-for="user in users"
    :key="user.id">
      {{ user.name }}
  </li>
</ul>

2.1.7 elements of multiple attribute s

The elements of multiple attributes should be written in multiple lines, one line for each attribute.

<!-- bad -->
<img src="https://vuejs.org/images/logo.png" alt="Vue Logo">
<MyComponent foo="a" bar="b" baz="c"/>

<!-- good -->
<img
  src="https://vuejs.org/images/logo.png"
  alt="Vue Logo">

<MyComponent
  foo="a"
  bar="b"
  baz="c"/>

2.1.8 simple expressions in templates

The component template should contain only simple expressions, and complex expressions should be refactored to evaluate properties or methods

Complex expressions can make your template less explicit. We should try to describe what should happen, not how to calculate that value. Moreover, computing properties and methods make the code reusable.

// bad
{{
  fullName.split(' ').map((word) => {
    return word[0].toUpperCase() + word.slice(1)
  }).join(' ')
}}

Better practices:

<!-- In template -->
{{ normalizedFullName }}

// Complex expression has been moved into a calculated property
computed: {
  normalizedFullName: function () {
    return this.fullName.split(' ').map(function (word) {
      return word[0].toUpperCase() + word.slice(1)
    }).join(' ')
  }
}

2.1.9 quoted attribute value

Non empty HTML attribute values should always be enclosed in double quotes.

<!-- bad -->
<input type=text>
<AppSidebar :style={width:sidebarWidth+'px'}>

<!-- good -->
<input type="text">
<AppSidebar :style="{ width: sidebarWidth + 'px' }">

2.1.10 abbreviations of directives

• Use: to represent v-bind:
• Use @ for v-on:
• Use # to represent v-slot:

<input
  :value="newTodoText"
  :placeholder="newTodoInstructions">

<input
  @input="onInput"
  @focus="onFocus">

<template #header>
  <h1>Here might be a page title</h1>
</template>

<template #footer>
  <p>Here's some contact info</p>
</template>

2.2 HTML

2.2.1 document template

HTML5 file template:

<!DOCTYPE html>
<html lang="zh-CN">
  <head>
    <meta charset="UTF-8">
    <title>HTML5 Standard template</title>
  </head>
  <body>
  </body>
</html>

Mobile terminal:

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
        content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, shrink-to-fit=no">
    <meta name="format-detection" content="telephone=no">
    <title>Mobile terminal HTML Template</title>

    <!-- S DNS Pre analysis -->
    <link rel="dns-prefetch" href="">
    <!-- E DNS Pre analysis -->

    <!-- S For online style page slice development, please directly cancel the annotation reference -->
    <!-- #include virtual="" -->
    <!-- E Online style page slice -->

    <!-- S Local debugging. Select the debugging mode according to the development mode. Please delete it -->
    <link rel="stylesheet" href="css/index.css">
    <!-- /Local debugging mode -->

    <link rel="stylesheet" href="http://srcPath/index.css">
    <!-- /Development machine debugging mode -->
    <!-- E Local debugging -->

</head>
<body>
</body>
</html>

PC end:

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="keywords" content="your keywords">
    <meta name="description" content="your description">
    <meta name="author" content="author,email address">
    <meta name="robots" content="index,follow">
    <meta http-equiv="X-UA-Compatible" content="IE=Edge,chrome=1">
    <meta name="renderer" content="ie-stand">
    <title>PC end HTML Template</title>

    <!-- S DNS Pre analysis -->
    <link rel="dns-prefetch" href="">
    <!-- E DNS Pre analysis -->

    <!-- S For online style page slice development, please directly cancel the annotation reference -->
    <!-- #include virtual="" -->
    <!-- E Online style page slice -->

    <!-- S Local debugging. Select the debugging mode according to the development mode. Please delete it -->
    <link rel="stylesheet" href="css/index.css">
    <!-- /Local debugging mode -->

    <link rel="stylesheet" href="http://srcPath/index.css">
    <!-- /Development machine debugging mode -->
    <!-- E Local debugging -->
</head>
<body>
</body>
</html>

2.2.2 closure of elements and labels

There are five types of HTML elements:

• Empty elements: area, base, br, col, command, embed ded, hr, img, input, keygen, link, meta, param, source, track, wbr
• Original text elements: script, style
• RCDATA elements: textarea, title
• Foreign elements: elements from MathML namespace and SVG namespace
• Regular elements: other elements allowed by HTML are called regular elements

In order to enable the browser to better parse the code and make the code more readable, there are the following conventions:

• All elements with start and end labels shall be written with start and end labels, and some elements that allow the omission of start labels or bundle labels shall also be written.
• Empty element labels are not marked with «/».

<!-- good -->
<div>
    <h1>I am h1 title</h1>
    <p>I am a text, I have a beginning and an end, and the browser can interpret it correctly</p>
</div>
 
<br data-tomark-pass>

<!-- bad -->
<div>
    <h1>I am h1 title</h1>
    <p>I am a text, I have a beginning but no end, and the browser can interpret it correctly
</div>

<br/>

2.2.3 code nesting

Element nesting specification, each block element has an independent line, and inline elements are optional.

<!-- good -->
<div>
    <h1></h1>
    <p></p>
</div> 
<p><span></span><span></span></p>

<!-- bad -->
<div>
    <h1></h1><p></p>
</div> 
<p> 
    <span></span>
    <span></span>
</p>

Paragraph and title elements can only nest inline elements.

<!-- good -->
<h1><span></span></h1>
<p><span></span><span></span></p>

<!-- bad -->
<h1><div></div></h1>
<p><div></div><div></div></p>

2.3 CSS

2.3.1 style file

• recommend:

@charset "UTF-8";
.jdc {}

• Not recommended:

/* @charset Rule does not start with the first character on the first line of the file */
@charset "UTF-8";
.jdc {}

/* @charset The rule is not in lowercase */
@CHARSET "UTF-8";
.jdc {}

/* No @ charset rule */
.jdc {}

2.3.2 code formatting

There are generally two types of style writing: one is Compact format and the other is Expanded format.

• Recommended: Expanded format

.jdc {
  display: block;
  width: 50px;
}

• Not recommended: Compact format

.jdc { display: block; width: 50px;}

2.3.3 code case

Style selectors, attribute names, attribute values and keywords are all written in lowercase letters, and attribute strings are allowed to use case.

• recommend:

.jdc {
  display: block;
}

• Not recommended:

.JDC {
  DISPLAY: BLOCK;
}

2.3.4 code legibility

1. There is a space between the left parenthesis and the class name, and a space between the colon and the attribute value.

• recommend:

.jdc {
  width: 100%;
}

• Not recommended:

.jdc{
  width:100%;
}

1. Comma separated values, followed by a space.

• recommend:

.jdc {
  box-shadow: 1px 1px 1px #333, 2px 2px 2px #ccc;
}

• Not recommended:

.jdc {
  box-shadow: 1px 1px 1px #333,2px 2px 2px #ccc;
}

1. Open a new line for a single CSS selector or new declaration.

• recommend:

.jdc, .jdc_logo, .jdc_hd {
  color: #ff0;
}

.nav{
  color: #fff;
}

• Not recommended:

.jdc, .jdc_logo, .jdc_hd {
  color: #ff0;
}.nav{
  color: #fff;
}

1. The color value rgb() rgba() hsl() hsla() rect() does not need spaces, and the value should not have unnecessary 0.

• recommend:

.jdc {
  color: rgba(255,255,255,.5);
}

• Not recommended:

.jdc {
  color: rgba( 255, 255, 255, 0.5 );
}

1. If the hexadecimal value of the attribute value can be abbreviated, use abbreviated as far as possible.

• recommend:

.jdc {
  color: #fff;
}

• Not recommended:

.jdc {
  color: #ffffff;
}

1. Do not specify units for 0.

• recommend:

.jdc {
  margin: 0 10px;
}

• Not recommended:

.jdc {
  margin: 0px 10px;
}

2.3.5 attribute value quotation marks

When quotation marks are required for CSS attribute values, single quotation marks shall be used uniformly.

• recommend:

.jdc {
  font-family: 'Hiragino Sans GB';
}

• Not recommended:

.jdc {
  font-family: "Hiragino Sans GB";
}

2.3.6 attribute writing suggestions

The following sequence is recommended:

1. Office location attribute: display / position / float / clear / visibility / overflow
2. Self attribute: width / height / margin / padding / border / background
3. Text attribute: color / font / text decoration / text align / vertical align / white space / break word
4. Other attributes (CSS3): content / cursor / border radius / box shadow / text shadow / background: linear gradient

.jdc {
  display: block;
  position: relative;
  float: left;
  width: 100px;
  height: 100px;
  margin: 0 10px;
  padding: 20px 0;
  font-family: Arial, 'Helvetica Neue', Helvetica, sans-serif;
  color: #333;
  background: rgba(0,0,0,.5);
  -webkit-border-radius: 10px;
  -moz-border-radius: 10px;
  -o-border-radius: 10px;
  -ms-border-radius: 10px;
  border-radius: 10px;
}

3.3.7 CSS3 browser private prefix

CSS3 browser private prefix comes first and standard prefix comes last.

.jdc {
  -webkit-border-radius: 10px;
  -moz-border-radius: 10px;
  -o-border-radius: 10px;
  -ms-border-radius: 10px;
  border-radius: 10px;
}

2.4 JavaScript

2.4.1 single line code block

Use spaces in single line blocks.

• Not recommended:

function foo () {return true}
if (foo) {bar = 0}

• recommend:

function foo () { return true }
if (foo) { bar = 0 }

2.4.2 brace style

In the process of programming, curly braces style is closely related to indentation style. There are many methods to describe the position of curly braces relative to code blocks. In JavaScript, there are three main styles, as follows:

• [recommended] One True Brace Style

if (foo) {
  bar()
} else {
  baz()
}

• Stroustrup

if (foo) {
  bar()
}
else {
  baz()
}

• Allman

if (foo)
{
  bar()
}
else
{
  baz()
}

2.4.3 spaces in code

1. Spaces before and after commas can improve the readability of the code. The team agreed to use spaces after commas and no spaces before commas.

• recommend:

var foo = 1, bar = 2

• Not recommended:

var foo = 1,bar = 2

var foo = 1 , bar = 2

var foo = 1 ,bar = 2

1. There cannot be a space between the key and value of an object literal, and a space is required between the colon and value of an object literal.

• recommend:

var obj = { 'foo': 'haha' }

• Not recommended:

var obj = { 'foo' : 'haha' }

1. Add a space before the code block.

• recommend:

if (a) {
  b()
}

function a () {}

• Not recommended:

if (a){
  b()
}

function a (){}

1. A space should be added before the parentheses of a function declaration.

• recommend:

function func (x) {
  // ...
}

• Not recommended:

function func(x) {
  // ...
}

1. Spaces are prohibited in function calls.

• recommend:

fn()

• Not recommended:

fn ()

fn
()

1. You need to add spaces before and after the operator

• recommend:

var sum = 1 + 2

• Not recommended:

var sum = 1+2

3, Annotation specification

Purpose of note:

• Improve the readability of the code, so as to improve the maintainability of the code
  Principles of notes:
• As short as possible if not necessary
• As long as necessary

3.1 HTML file comments

3.1.1 single line notes

It is generally used for simple descriptions, such as some state descriptions, attribute descriptions, etc.

There is a space character before and after the comment content. The comment is located above the code to be commented and occupies a separate line.

• recommend:

<!-- Comment Text -->
<div>...</div>

• Not recommended:

<div>...</div><!-- Comment Text -->

<div><!-- Comment Text -->
  ...
</div>

3.1.2 module notes

It is generally used to describe the name of the module and the position where the module starts and ends.

One space character before and after the comment content,
Indicates the start of the module,
Indicates the end of the module, with one line between modules.

• recommend:

<!-- S Comment Text A --> 
<div class="mod_a">
  ...
</div>
<!-- E Comment Text A -->
 
<!-- S Comment Text B --> 
<div class="mod_b">
  ...
</div>
<!-- E Comment Text B -->

• Not recommended:

<!-- S Comment Text A -->
<div class="mod_a">
  ...
</div>
<!-- E Comment Text A -->
<!-- S Comment Text B --> 
<div class="mod_b">
  ...
</div>
<!-- E Comment Text B -->

3.1.3 nested module notes

When module comments appear again in the module comments, nested modules are no longer used in order to highlight the main modules.

<!-- S Comment Text -->
<!-- E Comment Text -->

Instead, use

<!-- /Comment Text -->

Comments are written on a separate line at the bottom of the tag at the end of the module.

<!-- S Comment Text A -->
<div class="mod_a">
  
    <div class="mod_b">
        ...
    </div>
    <!-- /mod_b -->
     
    <div class="mod_c">
     ...
    </div>
    <!-- /mod_c -->
  
</div>
<!-- E Comment Text A -->

3.2 CSS file comments

3.2.1 single line notes

The first character and the last character of the comment content are a space character, which occupy a separate line, separated by a line.

• recommend:

/* Comment Text */ 
.jdc {} 

/* Comment Text */ 
.jdc {}

• Not recommended:

/*Comment Text*/
.jdc {
  display: block;
}

.jdc {
  display: block;/*Comment Text*/
}

3.2.2 module notes

The first character and the last character of the comment content are a space character, / * and module information description occupy one line, multiple horizontal separators — and * / occupy one line, and there are two lines between lines.

• recommend:

/* Module A
---------------------------------------------------------------- */
.mod_a {}


/* Module B
---------------------------------------------------------------- */
.mod_b {}

• Not recommended:

/* Module A ---------------------------------------------------- */
.mod_a {}
/* Module B ---------------------------------------------------- */
.mod_b {}

3.2.3 document notes

Note the page name, author, creation date and other information under the style file encoding declaration @ charset statement.

@charset "UTF-8";
/**
 * @desc File Info
 * @author Author Name
 * @date 2015-10-10
 */

3.3 JavaScript file comments

3.3.1 single line notes

Single line comments use / /. Comments should be written on a separate line above the annotated object and should not be appended to a statement.

• recommend:

// is current tab
const active = true

• Not recommended:

const active = true // is current tab

An empty line is required above the comment line (unless the top of a block is above the comment line) to increase readability.

• recommend:

function getType () {  
  console.log('fetching type...')
  
  // set the default type to 'no type'
  const type = this.type || 'no type'
  return type
}

// A blank line is not required when the top of a block is above the comment line
function getType () {  
  // set the default type to 'no type'
  const type = this.type || 'no type'   
  return type
}

• Not recommended:

function getType () {  
  console.log('fetching type...')
  // set the default type to 'no type'
  const type = this.type || 'no type'
  return type
}

3.3.2 multiline notes

Multiline comments use / * *… * /, not multiline / /.

• recommend:

/**
 * make() returns a new element
 * based on the passed-in tag name
 */
function make (tag) {
  // ...

  return element
}

• Not recommended:

// make() returns a new element
// based on the passed in tag name
function make (tag) {
  // ...

  return element
}

3.3.3 comment space

A space is required between the comment content and the comment character to increase readability. eslint: spaced-comment.

• recommend:

// is current tab
const active = true

/**
 * make() returns a new element
 * based on the passed-in tag name
 */
function make(tag) {  
  // ...

  return element
}

• Not recommended:

//is current tab
const active = true

/**
 *make() returns a new element
 *based on the passed-in tag name
 */
function make(tag) {  
  // ...

  return element
}

3.3.4 special marks

Sometimes we find a possible bug, but it can’t be fixed for some reasons; Or there are some functions to be completed in a certain place. At this time, we need to use the corresponding special tag comments to inform ourselves or partners in the future. There are two common special marks:

• //FIXME: explain what the problem is
• //TODO: explain what else to do or the solution to the problem

class Calculator extends Abacus {
  constructor () {
    super ()

      // FIXME: shouldn't use a global here
      total = 0

      // TODO: total should be configurable by an options param
      this.total = 0
  }
}

3.3.5 document notes

Document annotations, such as functions, classes, files, events, etc; All use the jsdoc specification.

/**
 * Book Class, representing a book
 * @constructor
 * @param {string} title - The title of a book
 * @param {string} author - The author of a book
 */
function Book (title, author) {
  this.title = title
  this.author = author
}

Book.prototype = {
  /**
   * Get the title of the book
   * @returns {string|*}
   */
  getTitle: function () {
    return this.title
  },
  /**
   * Set the number of pages in the book
   * @param pageNum {number} the number of pages
   */
  setPageNum: function (pageNum) {
    this.pageNum=pageNum
  }
}

3.3.6 annotation tools

ESLint is the most popular JS code checking tool at present. There are some annotation related rules in ESLint, which users can choose to open:

• valid-jsdoc

• require-jsdoc

• no-warning-comments

• capitalized-comments

• line-comment-position

• lines-around-comment

• multiline-comment-style

• no-inline-comments

• spaced-comment

4, Others

• Use two spaces to indent and wrap lines.
• It is recommended to add a semicolon at the end of JavaScript code for large team multi person collaborative projects.
• Small individual innovation and hand training projects can try to use the style without semicolon at the end of JavaScript code, which is more refreshing and concise.

If there are any mistakes, I hope you can remind me in the comments!!!
(the article comes from an article in the front end of the official account, «the most complete Vue front-end code style guide»).
Link address: https://mp.weixin.qq.com/s/2GLfEHXDTCOD1q-etlGMEQ