🤞 Promises Explained Like You're 5

I promise to call you when I'm done

Day 52 of 149

👉 Full deep-dive with code examples

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The Pizza Order

You order pizza for delivery.

The restaurant gives you a promise:

• "Your pizza will arrive" (pending)
• Eventually: "Pizza's here!" (fulfilled) 🍕
• Or: "Sorry, we're out of dough" (rejected) ❌

JavaScript promises work the same way!

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The Problem with Callbacks

Remember callback hell?

doA(function () {
  doB(function () {
    doC(function () {
      // 🌀 Spiral of doom
    });
  });
});

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Promises to the Rescue

doA()
    .then(() => doB())
    .then(() => doC())
    .then(() => done!)
    .catch((error) => handleError);

Flat! Readable! Error handling in one place!

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Three States

State	Meaning
Pending	Still working on it
Fulfilled	Success! Here's the result
Rejected	Failed! Here's the error

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Creating a Promise

const myPromise = new Promise((resolve, reject) => {
  if (success) {
    resolve("Here's your data!");
  } else {
    reject("Something went wrong!");
  }
});

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In One Sentence

Promises represent a future value that will eventually be available, making async code cleaner than callbacks.

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