iteration | web.dev

custom extension
- Iterable+ext
loop statements for iterations
- / / /
- ,
- - iterators must implement next() method.
- of an - iterables can make iterators.
- three types that are related to the .
  - - object that can be iterated.

JS ⟩ iteration

three types that are related to iteration：

iterable - object that can make iterators to loop over itself.
iterator - object that can produce the next iteration result.
iteration result - object that holds the result of each step of the iteration.

custom extension
- Iterable+ext
loop statements for iterations
- / / /
- ,
- - iterators must implement next() method.
- of an - iterables can make iterators.
- three types that are related to the .
  - - object that can be iterated.

💾 replit：iterator

let iterable = [1, 2, 3];

// ⭐️ iterate an iterable "the hard way"
let iterator = iterable[Symbol.iterator]();  // ⭐️ 1. make an iterator
let result = iterator.next();                // ⭐️ 2. first result

while (!result.done) {
    console.log(result.value);
    result = iterator.next();                // call next() repeatedly
}

// ⭐️ the easy way
for (const i of iterable) { console.log(i) } // 1, 2, 3

iterators only iterate once❗️ - iterators only iterate once.

iterable iterator - an iterator that is itself iterable.

IteratorPrototype - prototype of all built-in iterators.

Iterator - extension for (built-in) iterators.

iterator - object that performs the iteration.

iteration result - object that holds the result of each step of the iteration.

Generator - objects returned by generator function.