Strict equality (===)

BaselineWidely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

Thestrict equality (===) operator checks whether its two operands areequal, returning a Boolean result. Unlike theequality operator,the strict equality operator always considers operands of different types to bedifferent.

Try it

console.log(1 === 1);// Expected output: trueconsole.log("hello" === "hello");// Expected output: trueconsole.log("1" === 1);// Expected output: falseconsole.log(0 === false);// Expected output: false

Syntax

x === y

Description

The strict equality operators (=== and!==) provide theIsStrictlyEqual semantic.

If the operands are of different types, returnfalse.
If both operands are objects, returntrue only if they refer to thesame object.
If both operands arenull or both operands areundefined,returntrue.
If either operand isNaN, returnfalse.
Otherwise, compare the two operand's values:
- Numbers must have the same numeric values.+0 and-0are considered to be the same value.
- Strings must have the same characters in the same order.
- Booleans must be bothtrue or bothfalse.

The most notable difference between this operator and theequality(==) operator is that if the operands are of different types, the== operator attempts to convert them to the same type before comparing.

Examples

Comparing operands of the same type

"hello" === "hello"; // true"hello" === "hola"; // false3 === 3; // true3 === 4; // falsetrue === true; // truetrue === false; // falsenull === null; // true

Comparing operands of different types

"3" === 3; // falsetrue === 1; // falsenull === undefined; // false3 === new Number(3); // false

Comparing objects

const object1 = {  key: "value",};const object2 = {  key: "value",};console.log(object1 === object2); // falseconsole.log(object1 === object1); // true