JavaScript function return object to be used where the function was called

Question

I have a function like the following, but the function calling this one return undefined, I don't know why.

$.fileReader_g = function(file){
        var reader  = new FileReader(); 
        reader.onloadend = function(){
                return {
                        result:     reader.result, 
                        size:       file.size, 
                        name:       file.name
                }
            }

        if (file){
                reader.readAsDataURL(file);
        } else {
                console.log('Upload Failed');
        }
    }

The above is called by the following.

$(document).on('change', '.album_art_select', function(){
        var cow = $.fileReader_g($(this)[0].files[0]);
        console.log(cow);
    });

Where am I missing this?

You did not `return` anything from inside the `$.fileReader_g` function. The function does not return anything. — Louie Almeda, Nov 04 '15 at 11:16

score 1 · Accepted Answer · edited May 23 '17 at 12:14

1

You define two functions.

One you assign to $.fileReader_g. It does not have a return statement and will always return undefined.

The other you assign to reader.onloadend. It does have a return statement, but nothing is going to pay any attention to it.

See also How to return the response from an asynchronous call?.

edited May 23 '17 at 12:14

Community

1
1

answered Nov 04 '15 at 11:16

Quentin

914,110
126
1,211
1,335

JavaScript function return object to be used where the function was called

1 Answers1