Array.prototype[Symbol.iterator]()

Baseline Widely available

This feature is well established and works across many devices and browser versions. Itâs been available across browsers since 2016å¹´9æ.

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const array = ["a", "b", "c"];
const iterator = array[Symbol.iterator]();

for (const value of iterator) {
  console.log(value);
}

// äºæ³ãããçµæ: "a"
// äºæ³ãããçµæ: "b"
// äºæ³ãããçµæ: "c"

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array[Symbol.iterator]()

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HTML

html

<ul id="letterResult"></ul>

JavaScript

const arr = ["a", "b", "c"];
const letterResult = document.getElementById("letterResult");
for (const letter of arr) {
  const li = document.createElement("li");
  li.textContent = letter;
  letterResult.appendChild(li);
}

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const arr = ["a", "b", "c", "d", "e"];
const arrIter = arr[Symbol.iterator]();
console.log(arrIter.next().value); // a
console.log(arrIter.next().value); // b
console.log(arrIter.next().value); // c
console.log(arrIter.next().value); // d
console.log(arrIter.next().value); // e

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function logIterable(it) {
  if (typeof it[Symbol.iterator] !== "function") {
    console.log(it, "is not iterable.");
    return;
  }
  for (const letter of it) {
    console.log(letter);
  }
}

// Array
logIterable(["a", "b", "c"]);
// a
// b
// c

// String
logIterable("abc");
// a
// b
// c

// Number
logIterable(123);
// 123 is not iterable.