Advanced Functions Rest Callback HOF Pure Impure and IIFE
Continue your JavaScript Tutorial learning path with hands-on explanation, code practice, and quiz.
Course
JavaScript Tutorial
Estimated Time
8 min
Progress
10%
Track Position
7 / 73
Lesson Overview
Simple Explanation
Rest operator multiple args ko array me collect karta hai. Callback function dusre function ko pass hota hai. Higher order function function ko input/output banata hai. Pure function same input par same output deta hai; impure external state change karta hai. IIFE immediately run hoti hai.
Code Explanation
sumAll rest use karta hai, process callback leta hai, IIFE startup code chalati hai.
Output Description
Console me callback aur IIFE ka behavior nazar ayega.
Practice Exercise
Ek HOF banao jo number list le aur callback ke zariye transform kare.
Extra Explanation
Why This Matters
Advanced Functions Rest Callback HOF Pure Impure and IIFE is core to dynamic behavior. Strong fundamentals here help you build forms, API flows, and interactive UI with confidence.
Real-World Workflow
Complex features are usually split into small functions, then verified through focused logging and tiny test cases.
Common Mistakes to Avoid
Avoid uncontrolled globals, weak error handling, and ignored async states. Define clear input-output expectations for each function.
Example + Live Practice
<script>
const sumAll = (...nums) => nums.reduce((acc, n) => acc + n, 0);
function process(value, cb) {
return cb(value);
}
const pureDouble = (n) => n * 2;
let counter = 0;
function impureIncrement() {
counter++;
}
(function () {
console.log("IIFE executed once");
})();
console.log(sumAll(1, 2, 3, 4));
console.log(process(10, pureDouble));
impureIncrement();
console.log(counter);
</script>Try It Yourself
Test Your Knowledge
Quiz Coming Soon
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Save Your Work
Lesson ke end par apna code save karein. Dashboard me aap kabhi bhi is saved code ko dobara dekh sakte hain.