Map.prototype[@@iterator]()

¥Syntax

map[Symbol.iterator]()

¥Parameters

没有任何。

¥None.

¥Return value

与 Map.prototype.entries() 返回值相同：一个新的 可迭代的迭代器对象，它生成映射的键值对。

¥The same return value as Map.prototype.entries(): a new iterable iterator object that yields the key-value pairs of the map.

¥Examples

¥Iteration using for...of loop

请注意，你很少需要直接调用此方法。@@iterator 方法的存在使得 Map 对象成为 iterable，像 for...of 循环这样的迭代语法会自动调用该方法来获取要循环的迭代器。

¥Note that you seldom need to call this method directly. The existence of the @@iterator method makes Map objects iterable, and iterating syntaxes like the for...of loop automatically call this method to obtain the iterator to loop over.

const myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");

for (const entry of myMap) {
  console.log(entry);
}
// ["0", "foo"]
// [1, "bar"]
// [{}, "baz"]

for (const [key, value] of myMap) {
  console.log(`${key}: ${value}`);
}
// 0: foo
// 1: bar
// [Object]: baz

¥Manually hand-rolling the iterator

你仍然可以手动调用返回的迭代器对象的 next() 方法，以实现对迭代过程的最大控制。

¥You may still manually call the next() method of the returned iterator object to achieve maximum control over the iteration process.

const myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");

const mapIter = myMap[Symbol.iterator]();

console.log(mapIter.next().value); // ["0", "foo"]
console.log(mapIter.next().value); // [1, "bar"]
console.log(mapIter.next().value); // [Object, "baz"]

¥See also

• Map
• Map.prototype.entries()
• Map.prototype.keys()
• Map.prototype.values()
• Symbol.iterator
• 迭代协议