How == and === are different in JavaScript
By Tan Lee Published on Dec 18, 2024 259
In JavaScript, == and === are both comparison operators, but they behave differently.
== is the equality operator in JavaScript. It checks if two values are equal, but it performs type conversion if the values are of different types.
For example:
1 2 3 |
console.log(5 == '5'); // true (string '5' is converted to number 5)console.log(0 == false); // true (false is converted to 0)console.log(null == undefined); // true (considered equal in non-strict comparison) |
=== is the strict equality operator in JavaScript. It checks if two values are equal and of the same type, without performing any type conversion.
For example:
1 2 3 |
console.log(5 === '5'); // false (different types: number vs string)console.log(0 === false); // false (different types: number vs boolean)console.log(null === undefined); // false (different types) |
In summary, use == when you want to check for equality regardless of type, and use === when you want to check for both value and type equality. It is generally recommended to use === to avoid unexpected results caused by type conversion.
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