Get extension from filename like variable - JavaScript - jQuery

Question

I have a varable var file = "testfile.txt"; I am using the following script to find its extension and it works well:

var parts = file.split('.');
var flename = parts[0];
var ext = parts[1];

But if i have a filename with more than one dots, the logic sucks.. It will give txt for filename.txt, but not in the case of file.nam.e.txt or something else.

Anybody suggest me the simplest solution to do this using JavaScript and/or jQuery?

score 5 · Answer 1 · answered Jun 14 '11 at 11:08

Just so you get some alternatives, you can extract it with regular expressions too:

var full = "filename.ext.txt";

// Get all characters before the last dot
var filename = /.*(?=\.)/.exec(full);

// Get the part without dots on the end
var extension = /[^\.]*$/.exec(full);

// If there are no dots in the full name, filename will be empty and extension
// will contain the whole filename. Do some extra processing:
if(!filename){
    filename = full;
    extension = '';
}

score 3 · Answer 2 · answered Jun 14 '11 at 10:19

3

var ext = 'hibernate.cfg.xml';

var index = ext.lastIndexOf('.');// .xml

alert(ext.substring(index+1)); // xml

answered Jun 14 '11 at 10:19

Ravi Parekh

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score 2 · Answer 3 · answered Jun 14 '11 at 10:03

2

var parts = file.split('.')
  , ext = (parts.length > 1 ? parts.pop() : null)
  , filename = parts.join('.');

answered Jun 14 '11 at 10:03

Jonny Buchanan

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Shadow The GPT Wizard · Accepted Answer · 2011-06-14T10:01:13.580

1

Simple as that:

var ext = parts[parts.length - 1];

And as for the file name:

var flename = parts.slice(0, parts.length - 1).join(".");

Last but not least, I would also validate before that block of code that file is not empty to avoid exceptions.

Edit: another similar way that is more elegant:

var ext = parts.splice(-1).join();
var flename = parts.join(".");

Note that unlike the first approach, this will actually change the array parts so don't use it afterwards.

edited Jun 14 '11 at 10:01

answered Jun 14 '11 at 09:39

Shadow The GPT Wizard

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and what about filename without extension.. imean `filename` for `filename.txt`... Could you tell mehow to get that also.. :) – Alfred Jun 14 '11 at 09:42
@blaster cheers see my new edit as well to avoid chance for errors. This is my final answer now.. :) – Shadow The GPT Wizard Jun 14 '11 at 09:44
@Shadow, why not `var ext = parts.splice(-1).join();` and `var filename = parts.join(".");`? – mekwall Jun 14 '11 at 09:55
@Marcus because I wasn't familiar with `splice` enough, just recently began using `slice` actually. Thanks for the suggestion, will give it quick test and add to the answer. :) – Shadow The GPT Wizard Jun 14 '11 at 09:56
@Shadow, actually using only `var ext = parts.pop();` should do the trick :) – mekwall Jun 14 '11 at 09:57
@Marcus yeah, but `splice` is so much cooler! ;) – Shadow The GPT Wizard Jun 14 '11 at 10:02
1

@Shadow, haha! `splice` might be cooler, but `pop` is more correct ;) – mekwall Jun 14 '11 at 10:03
@Marcus well, there is now another answer with exactly that. So I'll leave my answer as is. :) – Shadow The GPT Wizard Jun 14 '11 at 10:06

Luc125 · Answer 5 · 2011-06-14T11:05:36.867

If file always contains at least one dot, you can use:

var ext = file.slice(file.lastIndexOf(".")+1);
var filename = file.slice(0,file.lastIndexOf("."));

And in a more general case, where file might contain no dot:

var ext = file.indexOf(".")<0?"":file.slice(file.lastIndexOf(".")+1);
var filename = file.indexOf(".")<0?file:file.slice(0,file.lastIndexOf("."));

And last, just for the sake of beautiful code:

var lastDotIndex = file.lastIndexOf(".");

if (lastDotIndex == -1) {    // Handles the case where there is no dot in "file"

    var fileExtension = "";
    var fileNameWithoutExtension = file;

} else {    // Common case 

    var fileExtension = file.slice(lastDotIndex+1);
    var fileNameWithoutExtension = file.slice(0,lastDotIndex);

}

score 0 · Answer 6 · answered Jun 14 '11 at 13:24

You've already gotten numerous working solutions, but I thought I'd contribute with a object-oriented solution that might be useful for more advanced scenarios:

var File = function(fname){
    if (typeof fname === "undefined") {
        console.log("You need to pass a filename or path to file");
        return false;
    }
    // Correct slashes
    fname = fname.replace("\\", "/", fname);
    this.org = fname;
    if (fname.lastIndexOf("/")) {
        this.path = fname.substr(0,fname.lastIndexOf("/")+1);
        fname = fname.substr(fname.lastIndexOf("/")+1);
    }
    this.ext = fname.substr(fname.lastIndexOf(".")+1);
    this.name = fname.substr(0, fname.lastIndexOf("."));
}

Then you can do the following:

var file = new File("/full/path/to/file/foo.bar.baz");

Now, access the properties with file.name, file.ext and file.path.

Get extension from filename like variable - JavaScript - jQuery

6 Answers6