Call javascript callback

Question

I want to pass an anonymous function as a callback, then call it. I am probably missing something simple, but I just get the error 'Uncaught type error - callback is not a function'. This is what I am doing - (using jQuery) - I pass the callback as an anonymous function when creating a new object:

$('#someid').alphaColorPicker({
            callback: function() {
                console.log("called")
            }
        });

Then I call it at some point (or try to):

$.fn.alphaColorPicker = function(callback) {

    ...
    ...

    callback(); //this throws the error
}

How do I correctly call the callback function? Thanks.

Quentin · Accepted Answer · 2016-06-20 10:32:17Z

3

Look at the value you are sending:

{ callback: function () { ... } }

That isn't a function.

It is an object with a property called callback which is a function.

Therefore:

callback.callback();

Or you could pass an actual function instead of an object:

$('#someid').alphaColorPicker(function() { console.log("called") });

answered Jun 20, 2016 at 10:32

Quentin

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Comments

gurvinder372 · Accepted Answer · 2016-06-20 10:31:58Z

0

You are not directly passing the function, you are passing an object which has callback property

make it

$.fn.alphaColorPicker = function(options) {

    ...

    options.callback(); //this throws the error
}

answered Jun 20, 2016 at 10:31

gurvinder372

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Comments

Jite · Accepted Answer · 2016-06-20 10:32:51Z

0

The thing you pass into the alphaColorPicker is not a callback function but rather a object containing a value that is a callback.

{ // When putting it within {} its a new object.
  // Where 'callback' is a member/key of the object.
  callback : function() {
    console.log("called");
}

If you instead pass the function directly:

$('#someid').alphaColorPicker(function() {
    console.log("called");
});

You can call it right away via callback();. If you wish to keep it as an object, you can call it by calling the member of the object instead of trying to call the object as a function:

callback.callback();

answered Jun 20, 2016 at 10:32

Jite

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2 Comments

ardmark Over a year ago

Thank you, I just kind of figured that out but your answer does explain why I was not getting anywhere - should have used callback.callback(), as you pointed out.

Jite Over a year ago

@ardmark, feel free to mark an answer as correct (and/or upvote) if any of them helped you to solve the issue.

ardmark · Accepted Answer · 2016-06-20 11:11:23Z

Found the problem, should not have passed the function as

callback: function() {
                console.log("called")
            }

But just like this:

    $('#' + boxID).alphaColorPicker(function() {
            console.log("hello")
    });

And if I want to pass parameters in, I can do it like this:

$('#' + boxID).alphaColorPicker({x:styleName, y:id, callback:function() {
        //do something
}});

But I am confused about how to pass parameters in / out like in jQuery event handlers such as:

$("#"+boxID).alphaColorPicker({x:styleName, y:this.inputID}, function(e){}

});

How do you access the callback here? In my example, in alphaColorPicker callback.x and callback.y are obviously available, but the callback function is passed as an object I can't see how to call it.

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