Each loop to find if function exists?

Question

    var a = {

        b: {
            aa: 'hello',
            bb: 'you',
            cc: 'guys'
            }

    }


    var b = function(){ 

        $.each(a.b, function(x){                

            if( $.isFunction(x) == 'function' ){
                alert(x);
            };

        });

    };

    var aa = function(){
        var dude = 'hi there';
    }

    b();

I have an each loop inside the b function.

What i would like to do is loop through the a.b values, and find if a function exists with it's name. In this case the only one that should trigger is 'aa' as function 'aa exists.

is the isfunction line correct? or would typeof work?

var aa and the aa within your a object are two completely different values due to namespace and scope. So if you are looking to find var aa within your object you need to push it into a.b — Scott Sword, Jun 17 '13 at 02:29

Jonathan Lonowski · Accepted Answer · 2013-06-17T02:53:15.053

2

In this case the only one that should trigger is 'aa' as function 'aa exists.

$.each() is iterating members of the Object passed to it. And, currently, the function aa is not a member of the Object a.b.

$.isFunction() isn't returning true because every member of a.b has a String value:

aa: 'hello',
bb: 'you',
cc: 'guys'

If you want the function as a member of the Object, you'll need to set it as the value of one of its properties:

a.b.aa = function () {
    var dude = 'hi there';
};

This will replace the 'hello' value with a reference to the function.

To reuse the property names to lookup globals, you can use them on the global object (window in browsers).

var key = 'aa';
var val = window[key];

var b = function () {
    $.each(a.b, function (key) {
        if (key in window && $.isFunction(window[key])) {
            alert(key + ' is a global function.');
        }
    });
};

Example: http://jsfiddle.net/cAaMf/

Though, note the "No wrap - in <body>" in the options of the Fiddle. This will only work for globals as no other scope object can be accessed within code.

edited Jun 17 '13 at 02:53

answered Jun 17 '13 at 02:29

Jonathan Lonowski

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Exactly, I was thinking using push, but this would be easier since JS object are mutable. – Scott Sword Jun 17 '13 at 02:31
Okay how do i 'break out' of iterating in the object passed? I want to check if a function exists in the global scope. – Robert Hane Jun 17 '13 at 02:38
You can return false from the callback. http://stackoverflow.com/questions/1784780/how-to-break-out-of-jquerys-each-loop – Brian Jun 17 '13 at 02:42
not break the loop, i meant search the global scope instead of the object passed – Robert Hane Jun 17 '13 at 02:43
1

@RobertHane: Just check for `"aa" in window && $.isFunction(window["aa"])`? – Bergi Jun 17 '13 at 02:44

Each loop to find if function exists?

1 Answers1