== vs === in JavaScript — Why Triple Equals Wins Every Time

Written by Rahul · Frontend Engineer at Google · Updated 2025

Short answer: always use ===. Long answer: understanding why will save you from some of the most bizarre bugs in JavaScript.

The Core Difference

• === (Strict Equality) — Compares value AND type. No conversions.
• == (Loose Equality) — Converts types first, then compares. Chaos follows.

The Type Coercion Madness

Here's the famous table of == insanity:

The Only Exception — null Checking

There's exactly ONE case where == is acceptable:

Real Production Bugs from ==

Bug 1: Form Validation

Bug 2: API Response Checking

Best Practices

1. Always use === and !== — no exceptions (ESLint rule: eqeqeq)
2. Convert types explicitly — Number(str), String(num), Boolean(val)
3. Use nullish coalescing (??) instead of == null checks
4. Enable ESLint — the eqeqeq rule catches these automatically

Interview Tip

Know the [] == ![] example and be able to explain the coercion steps. Then say "in practice, I always use strict equality and let the linter enforce it." That shows both knowledge and pragmatism.