Iterators and Generators: Real Use Cases

Added: 2026-05-21

[00:00:01]Iterators and generators.

[00:00:04]Real use cases.

[00:00:06]Use case one.

[00:00:08]Pagination.

[00:00:10]Function star fetch pages.

[00:00:12]Yield pages one at a time.

[00:00:15]Each call to next fetches the next page from the API.

[00:00:19]The caller uses a four of loop.

[00:00:21]It looks synchronous, but each iteration is a separate API call.

[00:00:25]Memory efficient.

[00:00:27]Only one page in memory at a time.

[00:00:30]Use case two.

[00:00:32]Infinite sequences.

[00:00:34]Function star Fibonacci.

[00:00:37]Generate Fibonacci numbers forever.

[00:00:40]Let a = 0, b = 1.

[00:00:43]While true, yield a, then swap.

[00:00:46]Use take to grab only what you need.

[00:00:49]Take 10 from Fibonacci gives the first 10 numbers.

[00:00:53]Use case three.

[00:00:55]Lazy processing.

[00:00:57]Function star filter, function star map.

[00:01:00]Chain them like array methods, but nothing executes until you consume the value.

[00:01:05]Process a million items, but only compute what you actually need.

[00:01:09]Use case four.

[00:01:11]State machines.

[00:01:14]Function star traffic light.

[00:01:16]While true, yield red, yield green, yield yellow.

[00:01:20]Each call to next advances the state.

[00:01:23]No variables tracking current state.

[00:01:26]The generator is the state.

[00:01:29]Use case five.

[00:01:31]Async iteration.

[00:01:33]Async function star stream data.

[00:01:36]Yield values as they arrive from a web socket or server sent events.

[00:01:40]For a wait of stream data gives you real-time data processing.

[00:01:44]Generators are underused.

[00:01:47]Once you see the pattern, you'll use them everywhere.

[00:01:50]Follow for more advanced JavaScript.