What is Promise ? 🤔

First forget computer.

Promise matlab wada.

Jaise mummy bolti hai —
“Padhai karo, shaam ko pizza milega.”

Ab pizza mila ya nahi mila, wo baad ki baat hai.
But mummy ne future ka ek wada kiya.

👉 JavaScript me bhi Promise exactly same cheez hai.

It is a thing that says:

“Abhi result nahi hai, but future me milega… ya fail bhi ho sakta hai.”

Bas itna hi.

Real Life Example 🍔

Suppose you ordered burger on Zomato.

Delivery boy ne bola:
“Bhaiya 20 min me aa raha hu.”

Ab teen possibilities hai:

⏳ 1. Pending (abhi kuch pata nahi)

Delivery boy raste me hai.

Burger mila? — ❌
Cancel hua? — ❌

Bas wait hi wait.

Ye hota hai Pending state

✅ 2. Fulfilled (burger aa gaya)

Door bell bajti hai 🔔

Delivery boy:
“Bhaiya burger le lo”

Ab wada pura ho gaya.

Ye hota hai Fulfilled

❌ 3. Rejected (burger nahi aaya)

Phone aata hai:

“Sir rider gir gaya… order cancel .”

Ab burger nahi milega.

Ye hota hai Rejected

Important Baat 🧠

Promise hamesha 3 state me hi hota hai:

• Pending → wait chal raha

• Fulfilled → success

• Rejected → fail

Aur ek baar decide ho gaya, fir change nahi hota.

Burger aa gaya to aa gaya.
Cancel ho gaya to ho gaya.

Delivery boy bol nahi sakta:

“Sir burger bhi le lo aur cancel bhi samajh lo.” 😂

Ab Computer Wala Part (Darr mat) 💻

Programing me kuch kaam time leta hai:

• Internet se data lana

• File download

• Server se baat karna

Computer bolta hai:

“Bhai tu apna kaam kar, result baad me dunga.”

Isliye Promise use hota hai.

Code Example (simple sa) 👶

const pizzaPromise = new Promise((resolve, reject) => {
  let shopOpen = true;

  if (shopOpen) {
    resolve("Pizza mil gaya 🍕");
  } else {
    reject("Shop band tha 😭");
  }
});

Isme:

• resolve = success

• reject = fail

Result kaise milega ? 🤷‍♂️

Computer khud nahi batata.

Tumko bolna padta hai:

👉 “Result aate hi bata dena.”

Uske liye .then() use hota hai.

pizzaPromise.then((msg) => {
  console.log(msg);
});

Agar success hua → message print

Agar fail ho gaya ? 😬

Tab use hota hai .catch()

pizzaPromise
  .then((msg) => console.log(msg))
  .catch((err) => console.log(err));

Success → then chalega
Fail → catch chalega

Funny Example 🤣

Exam ka result Promise jaisa hota hai.

Result day se pehle:

👉 Pending — mummy bhi tension me, tum bhi

Result aa gaya:

Pass → Fulfilled 🎉
Fail → Rejected 😭

Aur sabse funny:

Result change nahi hota.

Teacher ko bolke:

“Sir reject ko fulfill kar do please”
— nahi hota 😂

One More Real Example 😏

Crush ko message bhejna:

“Hi 🙂”

Reply nahi aaya → Pending
Reply “Hi” → Fulfilled 😍
Reply “Bhaiya bolu?” → Rejected 💀

🔥 Static Methods

Ab tak ek hi Promise tha.

Real life me ek sath bahut cheeze hoti hai.

Jaise Goa trip plan 😎

Promise.all() — Sab ayenge tabhi trip 🚗

Tumne 4 dost ko bola Goa chalte hai.

Rule: Sab ayenge tabhi jayenge

Ek bhi mana → trip cancel ❌

Promise.all([
  Promise.resolve("Rahul aa raha"),
  Promise.resolve("Aman aa raha"),
  Promise.reject("Kunal mana kar diya"),
  Promise.resolve("Rohit aa raha")
])
.then((data) => console.log("Trip pakki", data))
.catch(() => console.log("Trip cancel 😭"));

👉 Ek bhi reject → sab fail

Bilkul real life jaisa 😅

Promise.any() — Koi ek aa jaye bas 😭

Ab tum desperate ho.

“Bhai koi ek chal le mere sath”

Promise.any([
  Promise.reject("Rahul busy"),
  Promise.resolve("Aman aa raha"),
  Promise.reject("Kunal exam")
])
.then((data) => console.log("Trip ho gayi 😎", data))
.catch(() => console.log("Koi bhi nahi aya 💀"));

👉 Ek success mila → kaam ho gaya

Promise.allSettled() — Sabka result batao 📋

Ab tum sirf dekhna chahte ho:

Kaun aa raha
Kaun mana kar raha

Trip ho ya na ho, report chahiye.

Promise.allSettled([
  Promise.resolve("Rahul aa raha"),
  Promise.reject("Kunal mana"),
  Promise.resolve("Aman aa raha")
])
.then((data) => console.log(data));

Output type:

• Fulfilled → aa raha

• Rejected → mana

👉 Ye kabhi fail nahi hota
Bas sabka result de deta

Final Words 🫡

Agar aap non technical ho, ya programing nahi jante, to bas itna yaad rakho:

👉 Promise = Future ka wada

Success bhi ho sakta
Fail bhi ho sakta
Abhi wait chal raha hota

Bas JavaScript wale log isko fancy bana dete 😁

Agar ye samajh aa gaya to aap Promise concept samajh gaye.
Coding baad me bhi seekh sakte ho 👍

Chalo ab chai piyo ☕