How to Get File Extensions with JavaScript

How can I get file extensions with JavaScript?

Newer Edit: Lots of things have changed since this question was initially posted - there's a lot of really good information in wallacer's revised answer as well as VisioN's excellent breakdown

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Edit: Just because this is the accepted answer; wallacer's answer is indeed much better:

return filename.split('.').pop();

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My old answer:

return /[^.]+$/.exec(filename);

Should do it.

Edit: In response to PhiLho's comment, use something like:

return (/[.]/.exec(filename)) ? /[^.]+$/.exec(filename) : undefined;

Get the file extension in the JavaScript

You can split the name file by dot, and access last index:

function sendFunc_web() {
  var inp = document.getElementById('vasplus_multiple_files');
  var count = inp.files.length;
  for (var i = 0; i < inp.files.length; ++i) {
    var num = i + 1;
    var name = inp.files.item(i).name;
    console.log(name)
    let ext = ext[ext.length - 1]
    console.log(ext)
  }
}

Node.js get file extension

I believe you can do the following to get the extension of a file name.

var path = require('path')

path.extname('index.html')
// returns
'.html'

If you would like to get all extensions in a file name (e.g. filename.css.gz => css.gz), try this:

const ext = 'filename.css.gz'
  .split('.')
  .filter(Boolean) // removes empty extensions (e.g. `filename...txt`)
  .slice(1)
  .join('.')

console.log(ext) // prints 'css.gz'

javascript - get the filename and extension from input type=file

Use lastIndexOf to get the last \ as an index and use substr to get the remaining string starting from the last index of \

function getFile(filePath) {        return filePath.substr(filePath.lastIndexOf('\\') + 1).split('.')[0];    }
    function getoutput() {        outputfile.value = getFile(inputfile.value);        extension.value = inputfile.value.split('.')[1];    }

<input id='inputfile' type='file' name='inputfile' onChange='getoutput()'><br>    Output Filename <input id='outputfile' type='text' name='outputfile'><br>    Extension <input id='extension' type='text' name='extension'>

How can I get file extensions with JavaScript?

Newer Edit: Lots of things have changed since this question was initially posted - there's a lot of really good information in wallacer's revised answer as well as VisioN's excellent breakdown

---

Edit: Just because this is the accepted answer; wallacer's answer is indeed much better:

return filename.split('.').pop();

---

My old answer:

return /[^.]+$/.exec(filename);

Should do it.

Edit: In response to PhiLho's comment, use something like:

return (/[.]/.exec(filename)) ? /[^.]+$/.exec(filename) : undefined;

Extract filename and extension in js

You can use the split() function combined with pop() to get the file full name (name + extension) and detect the separation between your file name and extension with lastIndexOf() :

var str = '/vagrant/modules/americabuy/tranzilaNotifications/class/../../../a_tranzila/log/tranzila_2018-01-09_08-58-47.json';
function fileNameAndExt(str){  var file = str.split('/').pop();  return [file.substr(0,file.lastIndexOf('.')),file.substr(file.lastIndexOf('.')+1,file.length)]}
console.log(fileNameAndExt(str));

How to trim a file extension from a String in JavaScript?

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.

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