Comparison Operators

Syntax

a === b, a !== b, a > b, a <= b

Examples

console.log(5 == "5");   // true - "5" is coerced to a number
console.log(5 === "5");  // false - different types
console.log(0 == false); // true - false is coerced to 0
console.log(null == undefined);  // true
console.log(null === undefined); // false

console.log(10 > 5);   // true
console.log(10 <= 10); // true
console.log("apple" < "banana"); // true - lexicographic (alphabetical) comparison
console.log("10" < "9"); // true - compared as strings, not numbers!

Best practices

• Always prefer === and !== over == and != to avoid unpredictable type coercion bugs
• Be aware that comparing strings uses lexicographic (dictionary) order, which can surprise you with numeric-looking strings
• Use Object.is() for the rare edge cases where even === behaves unexpectedly (like NaN and -0)
• Explicitly convert types with Number() or String() before comparing rather than relying on implicit coercion

At a glance

Purpose

Application logic and interaction

File extension

.js · .mjs

Runs in

Browsers and JavaScript runtimes

Usually used with

HTML, CSS and Web APIs

Specifications & further reading

• ECMAScript specification

Related JavaScript documentation