Map.prototype.forEach()

20157

Map forEach() map /

function logMapElements(value, key, map) {
  console.log(`m[${key}] = ${value}`);
}

new Map([
  ["foo", 3],
  ["bar", {}],
  ["baz", undefined],
]).forEach(logMapElements);

// Expected output: "m[foo] = 3"
// Expected output: "m[bar] = [object Object]"
// Expected output: "m[baz] = undefined"

forEach(callbackFn)
forEach(callbackFn, thisArg)

callbackFn

map

value
key
map: map

thisArg

callbackFn this

undefined

forEach map callback undefined

callbackFn

value
key
Map

forEach thisArg callback this undefined this callback this this

forEach callback forEach

Map

Map

function logMapElements(value, key, map) {
  console.log(`map.get('${key}') = ${value}`);
}
new Map([
  ["foo", 3],
  ["bar", {}],
  ["baz", undefined],
]).forEach(logMapElements);
// 
// "map.get('foo') = 3"
// "map.get('bar') = [object Object]"
// "map.get('baz') = undefined"


ECMAScript 2027 LanguageSpecification # sec-map.prototype.foreach

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