Detect image suffix?

mat41 · July 26th, 2005, 03:35 AM

Hello Javascripters. Is there some client side method out there to detect an image suffix not using a string comparison?

My objective is to not allow any images other than .jpg and .gif files to be uploaded to an image library. I realize I can do this by massaging/comparing the string I get from the form element. Due to the case sensitivity of JS I would like to do it a bit smarter. Any ideas? This would also eliminate the possibility of awkward users uploading doc and other strange things that do not belong in an image library.

TYIA

Wind is your friend
Matt

ChrisScott · July 26th, 2005, 04:29 AM

Hi Matt,

Don't know of a way without string comparison, but you could use a case insensitive regular expression, something like...

Code:

function isImg(fileName){
    return /\.(gif|jpe?g)$/i.test(fileName);
}

HTH,

Chris

mat41 · July 26th, 2005, 07:32 PM

After reading my question I realized I asked it poorly. Nice work - Your answer is exactly what I was looking for. Thanking you very much and you have a fine day.

Wind is your friend
Matt

mat41 · July 27th, 2005, 08:57 PM

Chris My function is working however is not working with a mixture of case, what have I missed? My REG EX experience is poor, I should work on it:

    function validate()
    {
       if (document.updateForm.File1.value=="")
       {
          alert('Click browse to select a file for upload to proceed');
          updateForm.File1.focus();
          return (false);
       }
       if ((/.(gif|jpe?g)$/i.test(document.updateForm.File1.value))==false)
       {
           alert('You may only upload .jpg, .jpeg, or .gif images (in case sensitive)');
           return (false);
       }
           return(true);
    }

TYIA

Wind is your friend
Matt

ChrisScott · July 28th, 2005, 03:15 AM

Your function seems to work fine for me casewise - the i at the end of the expression makes the whole thing case insensitive. Can you give an example of what is failing e.g. a filename and whether it should pass / fail?

BTW the period at the start of the expression needs to be escaped - '\.' instead of '.', otherwise it will allow any character before the file extension.

Thanks,

Chris

mat41 · July 28th, 2005, 06:43 PM

I just tryed it on my laptop, things work fine there. The production machine is on Defence Restricted Network, I am experiencing some wierd caching issues that seem to be out of my control - I believe this is what made the function behave badly. Thanks again Chris

Wind is your friend
Matt