Javascript: onload event not reaching for javascript's FileReader API

Question

I need to create extract the signature of a file at the client level itself so as to positively determine its file type. Below is my file input object:

<input id="test1" type="file">

I wrote the following javascript code against it:

var fileInput = document.getElementById('test1');
fileInput.addEventListener('change', function(e) {
    console.log("file selected");
    var reader = new FileReader();
    reader.onload = function(e) {
        console.log("loaded");
        var file_slice = gcUploadFile.slice(0,4);
        console.log(file_slice);
        var arr_buffer = reader.readAsArrayBuffer(file_slice);
        console.log(arr_buffer);
    }
});

Check out the fiddle for the above.

The trouble I am having is that my code does not even enters the onload fucntion.

What am i doing wrong?

Note: I am coding only using plain javascript but i am open to use Google Closure.

adeneo · Accepted Answer · 2014-04-11 07:39:04Z

1

Why would it reach the onload handler, nothing is ever read by the FileReader.

You have to pass the file to the fileReader by reading it as something

var fileInput = document.getElementById('test1');
fileInput.addEventListener('change', function(e) {
    console.log("file selected");
    var reader = new FileReader();
    reader.onload = function(e) {
        console.log("loaded");
        var file_slice = gcUploadFile.slice(0,4);
        console.log(file_slice);
        var arr_buffer = reader.readAsArrayBuffer(file_slice);
        console.log(arr_buffer);
    }

    reader.readAsBinaryString(e.target.files[0]);

});

answered Apr 11, 2014 at 7:39

adeneo

319k29 gold badges410 silver badges392 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Javascript: onload event not reaching for javascript's FileReader API

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related