Why should you care?

Useful for infinite sequences, paging data, or readable custom iterators.

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function* countUp(max) {
  for (let i = 1; i <= max; i++) yield i;
}
for (const n of countUp(3)) console.log(n);

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What happened?

• yield sends a value out and pauses.
• The for...of loop resumes until done.

Practice next

1. Run countUp with for...of.
2. Manual gen.next() until done is true.
3. Compare memory vs building a huge array.
4. Write function* idGenerator() that yields incrementing IDs forever.
5. Pause a generator mid-loop and resume later with next().

Remember

function* syntax yield pauses execution Iterable with for...of

ScriptVerse infinite scroll

A generator fetches the next page of transactions on each yield, feeding a list as the user scrolls.

Outcome: Generators simplify lazy pagination compared to manual page counters everywhere.