Javascript syntax error unexpected token (file input)

Question

I am building a function to read from a file input using jQuery. I have gotten the function working, however I am receiving a syntax warning in the console. Here is my code:

function (el) {

    function () {
        var file = el.files[0];
        if (file) {
            read = new FileReader();
            read.readAsDataURL(file);
        }

        return read.result;
    }
}

It appears the error is occurring due to the code on line 3 function () {, and the error reads:

Uncaught SyntaxError: Unexpected token (

Any ideas?

what is the purpose of setting an anonymous function which is anyway not called? — A. Wolff
– A. Wolff, Commented Dec 17, 2017 at 14:39

t.niese · Accepted Answer · 2017-12-17 14:48:57Z

2

An anonymous function must be part of an expression, e.g. an assignment, immediatly called, or passed as argument.

But you do not use the anonymous in any way, and this is a syntax error.

At the given place only a named function would be valid, so the parser expects a function identifier but finds a ( and as of that it throws:

Uncaught SyntaxError: Unexpected token (

answered Dec 17, 2017 at 14:48

t.niese

41k9 gold badges78 silver badges111 bronze badges

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

4 Comments

easports611 Over a year ago

For some reason when I name the function, the code no longer works.

t.niese Over a year ago

@easports611 what do you mean with no longer works does your code work when the console shows the Uncaught SyntaxError: Unexpected token ( error?

easports611 Over a year ago

Yes, it works with the syntax warning, but dies not work when I name the function (but the warning goes away).

t.niese Over a year ago

@easports611 The complete file in which the SyntaxError occurs will not be executed. Therefore, the code responsible for functioning is not in that file. As soon as you fix the SyntaxError the whole code in that file is executed. So you need to check what in the file might break your code. But that's out of the scope of this question.

Ciro Spaciari · Accepted Answer · 2017-12-17 14:49:38Z

0

You need to name your functions like t.niese comment: An anonymous function must be part of an expression, e.g. an assignment, immediatly called, or passed as argument. But you do not use the anonymous in any way, and this is a syntax error.

function read(el) {

    function readFile() {
        var file = el.files[0];
        if (file) {
            read = new FileReader();
            read.readAsDataURL(file);
        }

        return read.result;
    }
}

answered Dec 17, 2017 at 14:49

Ciro Spaciari

6305 silver badges10 bronze badges

1 Comment

easports611 Over a year ago

I actually tried naming the function, and this breaks the functionality of the code (no visible errors, but data does not get sent to server.

Collectives™ on Stack Overflow

Javascript syntax error unexpected token (file input)

2 Answers 2

4 Comments

1 Comment

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

1 Comment

Related