What is the difference between == and ===?

== vs ===

=== (strict equality)

Compares value and type - no conversion.

js
1 === 1          // true
1 === '1'        // false - different types
null === null    // true
null === undefined // false

== (loose equality)

Compares values after type coercion - JavaScript converts types before comparing.

js
1 == '1'         // true - '1' converted to 1
0 == false       // true - false converted to 0
null == undefined // true - special rule
null == 0        // false - special rule
[] == false      // true - both convert to 0
'' == false      // true - both convert to 0

The coercion rules are complex

js
[] == ![]  // true - this is why == is confusing
// [] -> 0, ![] -> false -> 0

Object comparison

js
// both == and === compare references for objects
const a = { x: 1 };
const b = { x: 1 };
a == b  // false
a === b // false
a === a // true

Always use ===. The loose equality rules are confusing, hard to remember, and a common source of bugs. The only exception some teams make is x == null to check for both null and undefined at once.

updated Mar 8, 2026

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== vs ===#

=== (strict equality)

== (loose equality)

The coercion rules are complex

Object comparison

== vs ===