Map.prototype.has()

Map 实例的 has() 方法返回一个布尔值，指示此映射中是否存在具有指定键的元素。

¥The has() method of Map instances returns a boolean indicating whether an element with the specified key exists in this map or not.

Try it

¥Syntax

has(key)

¥Parameters

¥Return value

true 如果 Map 对象中存在具有指定键的元素；否则 false。

¥true if an element with the specified key exists in the Map object; otherwise false.

¥Examples

¥Using has()

const myMap = new Map();
myMap.set("bar", "foo");

console.log(myMap.has("bar")); // true
console.log(myMap.has("baz")); // false

Specification
ECMAScript Language Specification # sec-map.prototype.has

¥Specifications

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¥Browser compatibility

¥See also