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Set.prototype.size - JavaScript | MDN
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Set.prototype.size

Baseline Widely available

This feature is well established and works across many devices and browser versions. Its been available across browsers since 2015 7.

Set size () .

In this article

const set1 = new Set();
const object1 = {};

set1.add(42);
set1.add("forty two");
set1.add("forty two");
set1.add(object1);

console.log(set1.size);
// Expected output: 3

size Set . size undefined. , .

size

js
const mySet = new Set();
mySet.add(1);
mySet.add(5);
mySet.add("some text");

console.log(mySet.size); // 3

Specification
ECMAScript 2027 LanguageSpecification
# sec-get-set.prototype.size

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  2. Set
    1. Set()
    1. Set[Symbol.species]
    1. Set.prototype.add()
    2. Set.prototype.clear()
    3. Set.prototype.delete()
    4. Set.prototype.difference()
    5. Set.prototype.entries()
    6. Set.prototype.forEach()
    7. Set.prototype.has()
    8. Set.prototype.intersection()
    9. Set.prototype.isDisjointFrom()
    10. Set.prototype.isSubsetOf()
    11. Set.prototype.isSupersetOf()
    12. Set.prototype.keys()
    13. Set.prototype.symmetricDifference()
    14. Set.prototype.union()
    15. Set.prototype.values()
    16. Set.prototype[@@iterator]()
    1. Set.prototype.size
  8. Object/Function
    1. Function.prototype.apply()
    2. Function.prototype.bind()
    3. Function.prototype.call()
    4. Function.prototype.toSource()
    5. Function.prototype[@@hasInstance]()
    1. Function: displayName
    2. Function.prototype.length
    3. Function: name
    4. Function
    5. Function.arguments
    6. Function.prototype.caller
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toString()
    10. Object.prototype.valueOf()
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
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