IIFE (Immediately Invoked Function Expressions)

Last Updated: 22nd October 2025

IIFE is a function that runs immediately after it is defined. It does not need to be called separately.

Syntax:

(function () {
  // code here
})();

// Or
(() => {
  // code here
})();

Hinglish Tip 🗣: IIFE ka matlab hai “define karte hi run ho jao”. Ye mostly scope isolation ke liye use hota hai.

Example 1:

(function () {
  let msg = "Hello from IIFE!";
  console.log(msg);
})();

Example 2:

(function (name) {
  console.log("Hello " + name);
})("Sadhu");

Example 3:

(() => {
  console.log("I am an arrow IIFE!");
})();

💡 Quick Practice

  • Create an IIFE that adds two numbers and logs the result.
  • Try defining variables inside IIFE and access them outside (you should get an error).
  • Convert a normal function into an IIFE.
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