Where does a callback function in javascript get its arguments from?

Question

I am able to run a code like this

myObject.save(function(error, data){
    if(error){
      console.log(error);
    }
    else {
      console.log(data);
    }
});

What i don't understand is where the anonymous function get the arguments error and data from?

Does this answer your question? Where do the parameters in a javascript callback function come from? — Ooker
– Ooker, Commented Mar 30, 2024 at 8:22

JonnyRaa · Accepted Answer · 2014-12-23 10:57:30Z

4

Its from the thing that calls it - so save might look like this:

    function save(callback) {
        //do stuff

        var error = false;
        var data = {
            something: 'horse'
        };

        callback(error, data)
    }

There's no magic going on - its just a function call

answered Dec 23, 2014 at 10:57

JonnyRaa

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1 Comment

JonnyRaa Over a year ago

I guess the only thing to add here is that in javascript functions are first class citizens so you can pass them around just like you can other objects/ints etc.

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