Map.prototype[@@iterator]() - JavaScript 编辑

The initial value of the @@iterator property is the same function object as the initial value of the entries method.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Syntax

myMap[Symbol.iterator]

Return value

The map iterator function, which is the entries() function by default.

Examples

Using [@@iterator]()

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"]

Using [@@iterator]() with for..of

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

Specifications

Specification
ECMAScript (ECMA-262) The definition of 'Map.prototype[@@iterator]()' in that specification.

Browser compatibility

BCD tables only load in the browser

See also

• Map.prototype.entries()
• Map.prototype.keys()
• Map.prototype.values()