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.

Fasto

See: Regular expression to remove a file's extension and see also: How can i get file extensions with javascript? – Edmonds

Pretty much the same as #1992108. And unless you do one heck of a lot of these, worrying about efficiency is Premature Optimisation. – Empiric

In the age of ES6, also see the Path module – in case you are using nodejs or a proper transpilation – Faulkner

Answer 1

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.

Schoolmaster

I like this solution the best. It's clean, and I can use it cause I know the file extension is always .jpg. I was looking for something like Ruby's x[0..-5], and x.slice(0, -4) looks great! Thanks! And thank you to everyone else for all the other robust alternatives provided! – Fasto

this is not the optimal solution, please check other solutions below. – Disagreeable

And if you're not 100% sure about the length of the extension, then don't this: "picture.jpeg".slice(0, -4) -> "picture." – Fairweather

This is dangerous solution, cause you don't really know the length of the format. – Sunset

"If you know the length of the extension" It's been decades since this was an acceptable assumption to make. Don't use this anymore. – Jonette

@Jonette Sorry to reply so late, but this is a perfectly acceptable solution in situations where you know the length of the extension, and those situations DO exist despite what you may think. In my case I'm filtering out all files that don't end with ".js" so it's not like I'm going to somehow get a different extension length anyway. – Bise

Not working on files without extension. gave a hard time detecting this bug at work. – Gynoecium

filename.split('.').slice(0, -1).join('.') || filename works even for files without extension. – Spiniferous

Answer 2

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

x.replace(/\.[^/.]+$/, "")

Selffertilization

You probably want to also disallow / as a path separator, so the regexp is /\.[^/.]+$/ – Amberjack

This works for any length of file extension (.txt or .html or .htaccess) and also allows for the file name to contain additional period (.) characters. It wouldn't handle eg .tar.gz due to the extension itself containing a period. It's more common for a file name to contain additional periods than a file extension. Thanks! – Hartmann

@Vik There's a difference between the 'right answer' and the accepted answer. An accepted answer is just the answer that was helpful for the one who asked the question. – Buxtehude

I suppose that there may be issues with the Windows platform because there can be back slashes. So the regexp should be /\.[^/\\.]+$/. – Salim

@John Hartsock, I'm trying to use this with Adobe Extendscript and it's giving me a syntax error message and highlighting the ]+$ part. I think the ] is causing the problem. Does anyone know a workaround for this? I'm using it to append a string to the end of a file name before its extension so I can export graphics from an InDesign document. – Ahmedahmedabad

@Ahmedahmedabad sounds like you need to escape the ] – Selffertilization

What does [^/.] mean? – Brainstorming

@ElgsQianChen here is a great tool for you to help answer your question regexr.com – Selffertilization

@ElgsQianChen the stackoverflow answer you found to your problem uses regex, now you have two problems. regex.info/blog/2006-09-15/247 – Manville

Does not handle cases where the string does not contain an extension. – Falco

How does a answer with no explanation get hundreds of ups? – Reata

Answer 3

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;     //=> "hello"
path.parse(filename).ext;      //=> ".html"
path.parse(filename).base; //=> "hello.html"

Further explanation at Node.js documentation page.

Fulgor

This answer is pretty restricted to server-side node. If you try to use this in react code, it doesn't seem to import. – Wedlock

if you want to remove an extension from a path including the directories, you can do var parsed = path.parse(filename) followed by path.join(parsed.dir, parsed.name). – Brandenburg

Another possibility is let base = path.basename( file_path, path.extname( file_path ) ). – Goodspeed

Answer 4

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];

Tightfisted

?? You can have a filename ex: "summer.family.jpg" in that case split('.')[0] will return only a partial file name. I would remove that one from the answer, or clearly state underneath the issue for that example. @basarat ... – Nace

Something I do frequently regarding part splits: var parts = full_file.split("."); var ext = parts[parts.length-1]; var file = parts.splice(0,parts.length-1).join("."); – Ardyce

x.split(".") should not even be considered an answer. I know I use a '.' in almost all of my file naming conventions, i.e. 'survey.controller.js', or 'my.family.jpg'. – Functional

@Lee2808: Hence the warning of only one dot. This is simply meant to show that there are a number of approaches, depending on the application. I would certainly use one of the other methods in almost all cases. – Tightfisted

x = x.substr(0, x.lastIndexOf('.')); - you probably meant x = x.substring(0, x.lastIndexOf('.'));? – Byrn

@tborychowski When the first parameter is 0, substr and substring do the same thing. See: #3746015 – Tightfisted

"it works for this case" isn't always the same as "it's correct implementation" :-) substring's second parameter is indexEnd, substr takes length, so IMO substring fits better here. – Byrn

Ah, I was actually about to argue the same point until I realized that, yes, I have them backwards. So, yes, fair point. Why javascript uses 2 functions that are easily confused is beyond me. – Tightfisted

x = x.substring(0, x.lastIndexOf('.')); is my choice. Thank you! – Chamaeleon

Answer 5

I like this one because it is a one liner which isn't too hard to read:

filename.substring(0, filename.lastIndexOf('.')) || filename

Gourmont

I think this one is the best because it's really easy to understand – Shortstop

Answer 6

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);
}

Flung

Warning, this fails if there happens to be no filename extension. You're left with an empty string. – Disharmony

Shorter version that accounts for no dots. var f = x.substr(0, x.lastIndexOf('.')) || x; This works because an empty string is falsy, therefore it returns x. – Application

String.prototype.substr() is deprecated. Please use String.prototype.slice() or String.prototype.substring() instead. Documentation can be found here. – Chichihaerh

Answer 7

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.

Navaho

The path.parse answer is simpler. – Wenn

Answer 8

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('.')

Oppose

It should not be name.join('') but name.join('.'). You split by dot but join by comma, so hello.name.txt returns hello, name – Radioluminescence

filename.split(".").shift(); – Eudemon

Answer 9

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 + ""
}

Igbo

Answer 10

Another one-liner:

x.split(".").slice(0, -1).join(".")

Cavafy

Answer 11

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:

1. 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.
2. 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

var thePath = "http://stackoverflow.com/directory/subdirectory/filename.jpg";
theName = thePath.split("/").slice(-1).join().split(".").shift();
alert(theName);

working snippet 2: the file name with extension

var theNameWithExt = "filename.jpg";
theName = theNameWithExt.split("/").slice(-1).join().split(".").shift();
alert(theName);

working snippet 2: the file name with double extension

var theNameWithExt = "filename.tar.gz";
theName = theNameWithExt.split("/").slice(-1).join().split(".").shift();
alert(theName);

Foment

Answer 12

Here's another regex-based solution:

filename.replace(/\.[^.$]+$/, '');

This should only chop off the last segment.

Philbert

Answer 13

Simple one:

var n = str.lastIndexOf(".");
return n > -1 ? str.substr(0, n) : str;

Trubow

Answer 14

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(/(\.[^/.]+)+$/, "");

Fairweather

Answer 15

var fileName = "something.extension";
fileName.slice(0, -path.extname(fileName).length) // === "something"

Bentham

This is the only method so far that works for full paths: path/name.ext -> paht/name instead of just returning name, but I would rather do with with fs.parse although it is a bit more verbose: https://mcmap.net/q/49859/-how-to-trim-a-file-extension-from-a-string-in-javascript – Satiety

I like this answer... to add to it: If you know the extension beforehand (or if the extension is a variable, then I find it more readable to say: filename.slice(0, -'.zip'.length) or filename.slice(0, -extension.length). – Uptodate

Answer 16

• A straightforward answer, if you are using Node.js, is the one in the first comment.
• My task was I need to delete an image in Cloudinary from the Node server and I just need to get the image name only. Example:

const path = require("path")
const image=xyz.jpg;
const img= path.parse(image).name
console.log(img) // xyz

Fish

Answer 17

Node.js remove extension from full path keeping directory

https://mcmap.net/q/49859/-how-to-trim-a-file-extension-from-a-string-in-javascript 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://mcmap.net/q/49859/-how-to-trim-a-file-extension-from-a-string-in-javascript also achieves this, but I find this approach a bit more semantically pleasing.

Tested in Node.js v10.15.2.

Satiety

Answer 18

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('.')), '')

Irick

or path.split('.').pop() for one part file extensions – Flita

He was actually trying to get the file name, not the extension! – Irick

Answer 19

We might come across filename or file path with multiple extension suffix. Consider the following to trim them.

text = "/dir/path/filename.tar.gz"    
output = text.replace(/(\.\w+)+$/,"")

result of output: "/dir/path/filename"

It solves the file extension problem especially when the input has multiple extensions.

Etiology

Please read How do I write a good answer?. While this code block may answer the OP's question, this answer would be much more useful if you explain how this code is different from the code in the question, what you've changed, why you've changed it and why that solves the problem without introducing others. – Probationer

Answer 20

This might help...

const splitNameAndExtension = (fileName) => {
  const dotIndex = fileName.lastIndexOf(".");

  if (dotIndex === -1) {
    return { name: fileName, extension: "" };
  }

  const name = fileName.substring(0, dotIndex);
  const extension = fileName.substring(dotIndex + 1);

  return { name, extension };
};

const result = splitNameAndExtension("File A (1).txt");
console.log("result: ", result) // { name: "File A (1)", extension: "txt" }

Annihilator

Answer 21

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");

Enforcement

Answer 22

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;
}

Nerve

fails with hello.tar.gz, output is hellotar. – Cirrate

#AsifAli thanks you are right, I forgot to readd the file extension. I've updated the answer, I hope it works now. – Nerve

Answer 23

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

> filePath
'/User/HELLO/WORLD/FILENAME'
> fileName
'FILENAME'
> MYPATH
'/User/HELLO/WORLD/FILENAME.js'

Arethaarethusa

Answer 24

I like to use the regex to do that. It's short and easy to understand.

for (const regexPattern of [
  /\..+$/,  // Find the first dot and all the content after it.
  /\.[^/.]+$/ // Get the last dot and all the content after it.
  ]) {
  console.log("myFont.ttf".replace(regexPattern, ""))
  console.log("myFont.ttf.log".replace(regexPattern, ""))
}

/* output
myFont
myFont
myFont
myFont.ttf
*/

The above explanation may not be very rigorous. If you want to get a more accurate explanation can go to regex101 to check

• \..+$
• \.[^/.]+$

Andorra

Answer 25

Try this one .split('.')[0]

it worked for me

Apophyge

Your answer not only doesn’t add anything to the existing answers, but it’s also incorrect – Welcy

Answer 26

Another one liner - we presume our file is a jpg picture >> ex: var yourStr = 'test.jpg';

    yourStr = yourStr.slice(0, -4); // 'test'

Pythia

Answer 27

x.slice(0, -(x.split('.').pop().length + 1));

Therm

While this code may answer the question, providing additional context regarding why and/or how this code answers the question improves its long-term value. – Kaveri

Answer 28

name.split('.').slice(0, -1).join('.')

that's all enjoy your coding...

Imprimatur

This line of code is already included in this answer. – Fasto

Answer 29

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.

Aggy

"If you're going for performance, don't go for javascript at all" - What else are you suggesting to use in web applications..? – Anisole

He doesn't mention web applications. – Aggy

This question was asked and answer was posted in 2010, 7 years ago, and JavaScript was pretty much used only in web applications. (Node was just born, it didn't even had a guide or NPM at that time) – Anisole

;-) Still, if performance matters on tasks like this, you might consider doing this on the backend and process the results on the frontend. – Aggy