Overall Goal:

• Delay create karna: code ko kuch time wait karana.
• Promise-based delay (async/await compatible).

Single Line Solution:

• const sleep = (ms) => new Promise((r) => setTimeout(r, ms));

Part 1: Promise creation

• new Promise((r) => ...)
• Promise constructor: ek Promise object banata hai.
• r → resolve function (Promise ko success me convert karta hai).

Part 2: Delay setup

• setTimeout(r, ms)
• setTimeout → delay ke baad function execute karta hai.
• r → resolve function ko call karega (Promise complete).
• ms → milliseconds to wait.

How it works:

• await sleep(1000) → 1 second wait → Promise resolve.
• sleep(500).then(() => ...) → 0.5 second baad callback.

Real world:

• Loading states: "Please wait..." messages.
• Retry delays: failed requests ke baad wait karna.
• Animations: smooth transitions ke liye delay.