JavaScript - pass data to anonymous function

Question

I've a typical use case (may be too specific to my use case).

I've a piece of like this:

var x=0,y=10;

var data = {"callback" : function(x,y) {console.log(x,y)}}

some where in the code flow im asynchronously call above anonymous function

call(data.callback);

my problem is in second piece of code i don't have data of x,y to pass on while calling function. So, is there any way we can attach data(x,y variables data) while declaration of function itself?

Edit 1:

@Kursad Gulseven, because, to make it simple i showed like that.

But, in actual case, "data", "callback" are dynamic names. So, i can't simple use data.callback.

Though i do that, i can't have variables (with data), where i'm trying to call my anonymous function . Because calling anonymous function is again from another asynchronous function which is what issue here.

Hope its clear and makes some sense.

call(data.callback.bind(data, 1, true, "anything else u need")); you can also use call/apply at run-time, bind() composes a new function — dandavis
– dandavis, Commented Nov 4, 2014 at 6:50
@dandavis, your answer seems to solve my problem. let check it. — Prasad.CH
– Prasad.CH, Commented Nov 4, 2014 at 7:01

Tivie · Accepted Answer · 2014-11-04 07:10:23Z

1

Inject x and y in your data object, when they are available.

data = {
  x: null,
  y: null,
  "callback": function(x, y) {
    x = x || this.x;
    y = y || this.y;
    console.log(x, y);
  }
}

data.x = 0
data.y = 10;

// I'm assuming here you have a way to know how the "data" object is called
// and how to access it. (the obejct it's attached to)
// For simplicity, I used a global

var dataName = 'data',
  callbackName = 'callback';

//using a wrapper function without parameters, like in your example
// call(data.callback);


//calling without parameters
window['data']['callback']();

// calling with parameters
window[dataName][callbackName](15, 25);

Note: If you're obtaining x and y through some kind of async call, you might wanna check the promise pattern

edited Nov 4, 2014 at 7:10

answered Nov 4, 2014 at 6:57

Tivie

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Comments

jongo45 · Accepted Answer · 2014-11-04 07:18:29Z

1

I'm not sure why you can't set data.x and data.y then read those values as the other answer mentions. If that is unsatisfactory, then perhaps you could build a closure (a function with x and y preset) when you obtain x and y, like so:

function setCallback(x,y){
  return (function(){console.log(x,y);});
}
data.callback=setCallback(0,10);

data.callback is then the same function you have except with x and y preset to the example values you provided.

Executing data.callback(); then results in 0 10 in console.

answered Nov 4, 2014 at 7:18

jongo45

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