Question

127

How to detect file extension with javascript FileReader

rated 0 times [ 131] [ 4] / answers: 1 / hits: 41014 / 10 Years ago, sat, august 2, 2014, 12:00:00

I'm using javascript's FileReader and my customized function for reading an JPG-JPEG image,
My problem is that how it's possible to detect the file extension through my code below and give error to user if the file is not JPG-JPEG:

function readURL(input) {

  if (input.files && input.files[0]) {

    var reader = new FileReader();



    reader.onload = function (e) {

      alert('image has read completely!');

    }



    reader.readAsDataURL(input.files[0]);

  }

}

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alfredoc

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4 Years ago

answered 10 Years ago erinh · Accepted Answer

You can try this,
I changed your code as follows:

var fileTypes = ['jpg', 'jpeg', 'png', 'what', 'ever', 'you', 'want'];  //acceptable file types



function readURL(input) {

    if (input.files && input.files[0]) {

        var extension = input.files[0].name.split('.').pop().toLowerCase(),  //file extension from input file

            isSuccess = fileTypes.indexOf(extension) > -1;  //is extension in acceptable types



        if (isSuccess) { //yes

            var reader = new FileReader();

            reader.onload = function (e) {

                alert('image has read completely!');

            }



            reader.readAsDataURL(input.files[0]);

        }

        else { //no

            //warning

        }

    }

}