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

One reason: wrapping your code in an anonymous function allows you to create a module which distinguishes a public API from private functions and variables that are only used internally to the module. This avoids polluting the global namespace.

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

    function helper() {/*Some code here*/;}

    myApp.sayGoodbye = function() {
        helper()
        console.log("Goodbye");
    };
})();

I could say:

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

function helper() {/*Some code here*/;}

myApp.sayGoodbye = function() {
    helper()
    console.log("Goodbye");
};

But then the global scope includes a function called helper which is of no use to anyone using your module, and could lead to possible naming conflicts with other modules.

I could alternatively just include helper as a method of myApp.

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

myApp.helper = function() {/*Some code here*/;}

myApp.sayGoodbye = function() {
    this.helper()
    console.log("Goodbye");
};

However, I may wish to prevent users from directly calling helper, in which case this won't do.