- == (Double equals) is for loose equality. Returns true for somewhat logically equal operands. This is because their types are converted to same type before comparing.
- === (Triple equals) is for strict equality. Returns true if both operands are same type and value.
- != is for loose inequality. Performs type coercion like
== - !== is for strict inequality. Both type and value are involved.
Predictable Behavior
Recommended to use
===in most cases
Further comparison
| Operator | Description | Example | Result |
|---|---|---|---|
== | Converts operands to the same type before comparing. | 1 == '1' | true |
== | Converts true to 1 and false to 0 before comparing. | true == 1 | true |
== | Converts operands to numbers if one is a number. | 0 == false | true |
=== | Strict Equality: No type conversion, compares both value and type. | 1 === '1' | false |
=== | Both operands must be of the same type and value. | 1 === 1 | true |
=== | No type conversion; different types mean false. | true === 1 | false |
Confusing comparison
| Scenario | == (Double Equals) | === (Triple Equals) |
|---|---|---|
1 with "1" | true | false |
0 with "" | true | false |
null with undefined | true | false |
[1] with [1] | false | false |
({}) with ({}) | false | false |