JavaScript - Immutability & Memoization

Overview

Estimated time: 10–15 minutes

Immutability helps prevent bugs by avoiding side effects. Memoization caches results for performance.

Learning Objectives

• Understand immutability and its benefits.
• Implement memoization for expensive functions.

Prerequisites

• JavaScript - Temporal Dead Zone (TDZ)

Immutability Example

const arr = [1, 2, 3];
const newArr = [...arr, 4]; // arr is unchanged

Memoization Example

function memoize(fn) {
  const cache = {};
  return function(x) {
    if (cache[x] !== undefined) return cache[x];
    return (cache[x] = fn(x));
  };
}

Common Pitfalls

• Immutability can increase memory usage if not managed carefully.

Summary

Immutability and memoization are key for robust, high-performance JavaScript code.