How to trim a file extension from a String in JavaScript

Question

For example  assuming that x   filename jpg  I want to get filename  where filename could be any file name  Let s assume the file name only contains  a-zA-Z0-9-   to simplify     I saw x substring 0  x indexOf   jpg    on DZone Snippets  but wouldn t x substring 0  x length-4  perform better  Because  length is a property and doesn t do character checking whereas indexOf   is a function and does character checking

User · Answer

x length-4 only accounts for extensions of 3 characters   What if you have filename jpegor filename pl   EDIT   To answer    sure  if you always have an extension of  jpg  x length-4 would work just fine   However  if you don t know the length of your extension  any of a number of solutions are better more robust   x   x replace                OR  x   x substring 0  x lastIndexOf         OR   x   x replace                   1     OR  with the assumption filename only has one dot   parts   x match            x   parts 0     OR  also with only one dot   parts   x split       x   parts 0

User · Answer

Not sure what would perform faster but this would be more reliable when it comes to extension like  jpeg or  html  x replace

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Another one liner - we presume our file is a jpg picture    ex  var yourStr    test jpg        yourStr   yourStr slice 0  -4       test

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In node js  the name of the file without the extension can be obtained as follows  const path   require  path    const filename    hello html        path parse filename  name          gt   quot hello quot  path parse filename  ext           gt   quot  html quot  path parse filename  base      gt   quot hello html quot   Further explanation at Node js documentation page

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I would use something like x substring 0  x lastIndexOf        If you re going for performance  don t go for javascript at all  -p No  one more statement really doesn t matter for 99 99999  of all purposes

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Though it s pretty late  I will add another approach to get the filename without extension using plain old JS-  path replace path substr path lastIndexOf

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If you have to process a variable that contains the complete path  ex   thePath    http   stackoverflow com directory subdirectory filename jpg   and you want to return just  filename  you can use   theName   thePath split      slice -1  join   split      shift      the result will be theName     filename    To try it write the following command into the console window of your chrome debugger  window location pathname split      slice -1  join   split      shift    If you have to process just the file name and its extension  ex   theNameWithExt    filename jpg     theName   theNameWithExt split      shift      the result will be theName     filename   the same as above   Notes    The first one is a little bit slower cause performes more operations  but works in both cases  in other words it can extract the file name without extension from a given string that contains a path or a file name with ex  While the second works only if the given variable contains a filename with ext like filename ext but is a little bit quicker  Both solutions work for both local and server files    But I can t say nothing about neither performances comparison with other answers nor for browser or OS compatibility   working snippet 1  the complete path  x000D   x000D  var thePath    http   stackoverflow com directory subdirectory filename jpg   x000D  theName   thePath split      slice -1  join   split      shift    x000D  alert theName   x000D     x000D   x000D   x000D    working snippet 2  the file name with extension  x000D   x000D  var theNameWithExt    filename jpg   x000D  theName   theNameWithExt split      slice -1  join   split      shift    x000D  alert theName   x000D     x000D   x000D   x000D    working snippet 2  the file name with double extension  x000D   x000D  var theNameWithExt    filename tar gz   x000D  theName   theNameWithExt split      slice -1  join   split      shift    x000D  alert theName   x000D     x000D   x000D   x000D

User · Answer

var fileName    something extension   fileName slice 0  -path extname fileName  length          something

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You can use path to maneuver   var MYPATH     User HELLO WORLD FILENAME js   var MYEXT     js   var fileName   path basename MYPATH  MYEXT   var filePath   path dirname MYPATH          fileName    Output   gt  filePath   User HELLO WORLD FILENAME   gt  fileName  FILENAME   gt  MYPATH   User HELLO WORLD FILENAME js

User · Answer

Another one-liner   x split      slice 0  -1  join

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If you know the length of the extension  you can use x slice 0  -4   where 4 is the three characters of the extension and the dot   If you don t know the length  John Hartsock regex would be the right approach  If you d rather not use regular expressions  you can try this  less performant   filename split      slice 0  -1  join       Note that it will fail on files without extension

User · Answer

You can perhaps use the assumption that the last dot will be the extension delimiter   var x    filename jpg   var f   x substr 0  x lastIndexOf          If file has no extension  it will return empty string  To fix that use this function  function removeExtension filename       var lastDotPosition   filename lastIndexOf           if  lastDotPosition     -1  return filename      else return filename substr 0  lastDotPosition

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This works  even when the delimiter is not present in the string   String prototype beforeLastIndex   function  delimiter        return this split delimiter  slice 0 -1  join delimiter     this          image  beforeLastIndex          image   image jpeg  beforeLastIndex          image   image second jpeg  beforeLastIndex          image second   image second third jpeg  beforeLastIndex          image second third    Can also be used as a one-liner like this   var filename    this is a filename txt   console log filename split      slice 0 -1  join         filename          EDIT  This is a more efficient solution   String prototype beforeLastIndex   function  delimiter        return this substr 0 this lastIndexOf delimiter      this

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Here s another regex-based solution   filename replace                     This should only chop off the last segment

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x slice 0  - x split      pop   length   1

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In Node js versions prior to 0 12 x   path basename filename  path extname filename    Of course this also works in 0 12 x and later

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Node js remove extension from full path keeping directory  https   stackoverflow com a 31615711 895245 for example did path hello html -  hello  but if you want path hello html -  path hello  you can use this      usr bin env node const path   require  path    const filename    path hello html   const filename parsed   path parse filename   console log path join filename parsed dir  filename parsed name      outputs directory as well   path hello   https   stackoverflow com a 36099196 895245 also achieves this  but I find this approach a bit more semantically pleasing   Tested in Node js v10 15 2

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I don t know if it s a valid option but I use this   name   filename split          trimming with pop   name pop       getting the name with join   name join          we split by     and we join by     to restore other eventual points    It s not just one operation I know  but at least it should always work   UPDATE  If you want a oneliner  here you are    name split      slice 0  -1   join

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Simple one   var n   str lastIndexOf       return n  gt  -1   str substr 0  n    str

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I like this one because it is a one liner which isn t too hard to read   filename substring 0  filename lastIndexOf          filename

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This is the code I use to remove the extension from a filename  without using either regex or indexOf  indexOf is not supported in IE8   It assumes that the extension is any text after the last     character   It works for    files without an extension   myletter  files with     in the name   my letter txt  unknown length of file extension   my letter html    Here s the code   var filename    my letter txt     some filename  var substrings   filename split          split the string at     if  substrings length    1      return filename     there was no file extension  file was something like  myfile    else     var ext   substrings pop       remove the last element   var name   substrings join         rejoin the remaining elements without separator   name     name  ext   join          readd the extension   return name

User · Answer

This is where regular expressions come in handy  Javascript s  replace   method will take a regular expression  and you can utilize that to accomplish what you want       assuming var x   filename jpg or some extension x   x replace                   1

User · Answer

The accepted answer strips the last extension part only   jpeg   which might be a good choice in most cases   I once had to strip all extensions   tar gz  and the file names were restricted to not contain dots  so 2015-01-01 backup tar would not be a problem    var name    2015-01-01 backup tar gz   name replace

[javascript] How to trim a file extension from a String in JavaScript?

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