The has()
method of Set
instances returns a boolean indicating whether an element with the specified value exists in this set or not.
The has()
method of Set
instances returns a boolean indicating whether an element with the specified value exists in this set or not.
has(value)
value
The value to test for presence in the Set
object.
Returns true
if an element with the specified value exists in the Set
object; otherwise false
.
const mySet = new Set(); mySet.add("foo"); console.log(mySet.has("foo")); // true console.log(mySet.has("bar")); // false const set1 = new Set(); const obj1 = { key1: 1 }; set1.add(obj1); console.log(set1.has(obj1)); // true console.log(set1.has({ key1: 1 })); // false, because they are different object references console.log(set1.add({ key1: 1 })); // now set1 contains 2 entries
Desktop | Mobile | Server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | Deno | Node.js | ||
has |
38 | 12 | 13 | 25 | 8 | 38 | 14 | 25 | 8 | 3.0 | 38 | 1.0 | 0.12.0 |
© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/has