Lesson 16 — Promise chaining

One step after another

Each .then returns a new Promise holding whatever its callback returned. That means you can chain steps: the next .then receives the previous result. If any step throws, a .catch at the end handles it.

Promise.resolve("ann")
  .then((s) => s.toUpperCase())
  .then((s) => console.log(s)); // ANN

Why it matters: fetch code is usually a chain — get the response, read the JSON, use the data — so you must know how values flow down it.