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LetsGit.IT/Categories/JavaScript
JavaScripteasy

What is the difference between == and === in JavaScript?

Tags
#equality#coercion
Back to categoryPractice quiz

Answer

== does type coercion before comparison, while === compares both value and type without coercion.

Advanced answer

Deep dive

Expanding on the short answer — what usually matters in practice:

  • Context (tags): equality, coercion
  • Explain the "why", not just the "what" (intuition + consequences).
  • Trade-offs: what you gain/lose (time, memory, complexity, risk).
  • Edge cases: empty inputs, large inputs, invalid inputs, concurrency.

Examples

A tiny example (an explanation template):

// Example: discuss trade-offs for "what-is-the-difference-between-==-and-===-in-jav"
function explain() {
  // Start from the core idea:
  // == does type coercion before comparison, while === compares both value and type without co
}

Common pitfalls

  • Too generic: no concrete trade-offs or examples.
  • Mixing average-case and worst-case (e.g., complexity).
  • Ignoring constraints: memory, concurrency, network/disk costs.

Interview follow-ups

  • When would you choose an alternative and why?
  • What production issues show up and how do you diagnose them?
  • How would you test edge cases?

Related questions

JavaScript
What is type coercion? Give a surprising example.
#coercion#types