IIFE (Immediately Invoked Function Expression)

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

It is a design pattern which is also known as a Self-Executing Anonymous Function and contains two major parts:

The first is the anonymous function with the lexical scope enclosed within the Grouping Operator (). This prevents accessing variables within the IIFE idiom as well as polluting the global scope.

The second part creates the immediately invoked function expression () through which the JavaScript engine will directly interpret the function.

For example,

(function () {
    console.log("This is Immediately Invoked Function");
 })();

The above function will automatically run when you open a browser or refresh the browser.

Pass Argument in IIFE:

(function (name) {
    console.log('This is Immediately Invoked Function,Created by '+name );
 })('Jigar');
//Output : This is Immediately Invoked Function,Created by Jigar

Use cases :

When you want your data ta be private

Want to call the function on page load