Immediately-Invoked Function [removed]IIFE) vs not

Question

I see a lot of code like:

var myApp ={};
(function() {
    console.log(\"Hello\");
    this.var1 = \"mark\";     //\"this\" is global, because it runs immedi         


        

Answer 1

Usually, you would have this :

        var myApp ={};
        (function() {
            console.log("Hello");
            var var1 = "mark";  
            myApp.sayGoodbye = function() {
                console.log("Goodbye");
            };
        })();

The main difference is that var1 doesn't clutter the global namespace. After this call, var1 is still the same than before (generally undefined).

As var1 can only be accessed from the function defineds in the closure, it is said "private".

Apart avoiding possible causes of conflicts, it's just cleaner not to keep global variables when useless.

Here, you don't have a local variable but a global one defined as this.var1. It's probably a bug, or the reason would be found elsewhere in the code.