IIFE (Immediately Invoked Function Expression) inJavaScript function

Introduction

An IIFE (Immediately Invoked Function Expression) is a JavaScript function that runs as soon as it is defined.

(function () {
    statements
})();

Examples

The function becomes a function expression which is immediately executed. The variable within the expression can not be accessed from outside it.

(function () {
    var aName = "Barry";
})();
// Variable name is not accessible from the outside scope
aName // throws "Uncaught ReferenceError: aName is not defined"

Assigning the IIFE to a variable stores the function's return value, not the function definition itself.

var result = (function () {
    var name = "Barry"; 
    return name; 
})(); 
// Immediately creates the output: 
result; // "Barry"

 Link

• IIFE
• StackOverflow