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(===) - JavaScript | MDN

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(===)

Baseline Widely available

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

(===) , , . .

In this article

console.log(1 === 1);
// Expected output: true

console.log("hello" === "hello");
// Expected output: true

console.log("1" === 1);
// Expected output: false

console.log(0 === false);
// Expected output: false

js
x === y

(=== !==) .

  • , false.
  • , true .
  • null undefined, true.
  • NaN, false.
  • :
    • . +0 -0 .
    • , .
    • true false.

(==) , , == .

js
"hello" === "hello"; // true
"hello" === "hola"; // false

3 === 3; // true
3 === 4; // false

true === true; // true
true === false; // false

null === null; // true

js
"3" === 3; // false
true === 1; // false
null === undefined; // false
3 === new Number(3); // false

js
const object1 = {
  key: "value",
};

const object2 = {
  key: "value",
};

console.log(object1 === object2); // false
console.log(object1 === object1); // true

Specification
ECMAScript 2027 LanguageSpecification
# sec-equality-operators


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