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Comparison Operators

Comparison Operators

Introduction

Comparison operators compare two values and return a boolean (true or false). They are fundamental to decision-making in code.

Visual Explanation

flowchart TD
    A["5 === '5'"] --> B["false — strict equality"]
    C["5 == '5'"] --> D["true — loose equality"]
    E["5 > 3"] --> F["true — greater than"]
    G["5 < 3"] --> H["false — less than"]

Strict vs Loose Equality

// Strict (recommended) — checks value AND type
5 === 5;    // true
5 === '5';  // false — different types
5 !== '5';  // true

// Loose (avoid) — coerces types
5 == '5';   // true — coercive comparison
5 != '5';   // false

Relational Operators

5 > 3;    // true
5 >= 5;   // true
3 < 5;    // true
3 <= 5;   // true

String Comparison

'apple' < 'banana';  // true — lexicographic order
'Apple' < 'apple';   // true — uppercase < lowercase

Best Practices

Always use === and !== instead of == and !=
Be careful with floating-point comparisons
Use Object.is() for NaN comparisons

Summary

=== checks value and type (strict)
== checks value with coercion (loose)
Always prefer ===
Relational operators work on numbers and strings

Further Reading

MDN: Comparison Operators