What is the difference between globally declaring a function and using window.myfunc = myfunc

What is the difference between the following 2 examples of code:

(function(){
    var myFunc = (function(){
        //do something
    })();
    window.myFunc = myFunc;
})();

and

var myFunc = (function(){
    //do something
})();

Solution

The two ways are really similar, but there is a small difference on how the myFunc global variable is created.

In the second way, using the var statement, will create the myFunc variable as a non-deleteable property of the global object, the var statement explicitly sets the internal {DontDelete} attribute , e.g.:

var myFunc = (function(){
    //do something
})();

delete window.myFunc; // false

While the first one can be deleted:

(function(){
    var myFunc = (function(){
        //do something
    })();
    window.myFunc = myFunc;
})();

//...
delete window.myFunc; // true

If you try the above in Firebug, both can be deleted, thats because Firebug uses code evaluation (eval) in the console.

You can check the above example here.