Using regex to validate file

Question

I am trying to validate image files before they are uploaded using javascript/jquery.

Here is what I have so far:

$('#cropimages').click(function(){
    i = 1 ;
    var valid = new RegExp('/^.*\.(jpg|jpeg|png|gif)$/') ;
    $('input').each(function(){

        if($(this).attr('name') == 'file'+i)
        {
            val = $(this).val() ;

            r = valid.exec(val) ;
            alert(r) ;
            i++ ;
        }
    })
    //$('#topperform').submit()
})

But it keeps coming back null no matter what kind of file I choose.

What do I need to do to my RegExp to make this work?

By the way, I would make your regular expression case insensitive var valid = /^.*\.(jpg|jpeg|png|gif)$/i; just in case your file contains extensions in uppercase like .JPG — Bruno
– Bruno, Commented Dec 21, 2012 at 12:55

Mark Byers · Accepted Answer · 2012-12-21 12:34:53Z

6

Use a regular expression literal:

var valid = /^.*\.(jpg|jpeg|png|gif)$/;

If you really want to use the RegExp consturctor then omit the delimiters.

var valid = new RegExp('^.*\.(jpg|jpeg|png|gif)$');

Related

Regular Expressions - Javascript (MDN)

answered Dec 21, 2012 at 12:34

Mark Byers

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1 Comment

Graham Over a year ago

One tiny thing; you don't need the new keyword when instantiating a RegExp :)

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