In programming, especially in JavaScript, =, ==, and === are different operators used for assignment and comparison, with distinct functionalities.
1. = (Assignment Operator)
The single = is an assignment operator. It assigns the value on the right to the variable on the left.
let value = 10;
value; // 10
console.log(value); // 10
2. == (Equality Operator)
The double == is an equality operator. It compares two values for equality after type coercion. If the types are different, JavaScript tries to convert them to the same type before comparison.
console.log(5 == '5'); // true
console.log(null == undefined); // true
console.log(0 == false); // true
3. === (Strict Equality Operator)
The triple === is a strict equality operator. It checks for both value and type equality without type coercion. If the types are different, it returns false immediately.
console.log(5 === '5'); // false
console.log('5' == 5); // true
console.log(null === undefined); // false
console.log(0 === false); // false
Summary
- = is for assignment.
- == checks for equality with type coercion.
- === checks for strict equality without type coercion (value and type must both match).
| Operator |
Name |
Checks |
Type Conversion |
Example (5 and "5") |
| = |
Assignment |
N/A |
N/A |
let x = 5; |
| == |
Equality |
Value |
Yes |
5 == "5" → true |
| === |
Strict Equality |
Value and Type |
No |
5 === "5" → false |
In JavaScript, it’s generally safer to use === for comparisons to avoid unexpected results due to type coercion.
Use == only when you specifically want type conversion to occur.