JavaScript · Chapter 28 of 55
JavaScript Comparison Operators
Comparison operators compare two values and return a boolean. `==` and `!=` perform type coercion before comparing, while `===` and `!==` (strict equality) compare both value and type without coercion.
Best practice is to always use `===` and `!==` to avoid confusing bugs caused by implicit type conversion.
Loose vs strict equality
`5 == '5'` is true because == coerces types before comparing, but `5 === '5'` is false since the types differ (number vs string).
Relational operators
`<`, `>`, `<=`, `>=` compare numbers or strings (lexicographically) and return booleans.
Example 1 (javascript)
console.log(5 == "5");
console.log(5 === "5");Output
true
false== coerces types; === requires matching type and value.
Example 2 (javascript)
console.log(10 > 5);
console.log("apple" < "banana");Output
true
trueStrings compare lexicographically, like dictionary order.
Key points
- `===` and `!==` check both value and type (strict).
- `==` and `!=` coerce types before comparing (loose).
- Always prefer strict equality to avoid surprising bugs.
- Strings compare lexicographically using Unicode code points.
💡 Note: '==' comparing null and undefined returns true, but === returns false — one more reason to prefer strict equality.