Schneider Electric·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Jun 2026

Summary

Interviewed for a software engineer role at Schneider Electric and got a classic JavaScript fundamentals question. Nothing crazy, but it made me realize how sloppy my mental model of type coercion actually was.

Questions Asked (1)

What is the difference between == and === in JavaScript? Cover how each compares values, what type coercion means and how it applies to ==, examples where they produce different results, and which one you'd recommend using.

Technical Trade-offsAPI & Integrations

Author's notes

Knew the surface answer but stumbled when they pushed on specific coercion examples.

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AI HintsAI Generated

Suggested Approach

Start by defining both operators clearly: === is strict equality (no type coercion) while == is loose equality (performs type coercion). Explain type coercion with concrete examples, then highlight the trade-offs and recommend === for predictability and avoiding bugs.

Pro tip: Mention that while == can be useful for null/undefined checks, using === consistently makes code more maintainable and aligns with modern best practices like ESLint's eqeqeq rule.

1. Define the operators

State that === checks both value and type without coercion, while == checks value after coercing types if they differ.

2. Explain type coercion

Describe how == converts operands to a common type (e.g., string to number) before comparison, and mention the abstract equality algorithm.

3. Provide examples

Give clear examples like 1 == '1' (true) vs 1 === '1' (false), null == undefined (true) vs null === undefined (false), and NaN comparisons.

4. Discuss trade-offs

Highlight that == can lead to unexpected results due to coercion, while === is more predictable and avoids subtle bugs.

5. Recommend an operator

Recommend using === by default, but note that == can be acceptable for checking null or undefined in one go.

Key Points to Mention

=== is strict equality, == is loose equality with type coercion
Type coercion converts operands to the same type before comparison
Examples: 1 == '1' is true, 1 === '1' is false; null == undefined is true, null === undefined is false
== can lead to unexpected results due to coercion rules (e.g., '' == 0 is true)
=== is generally recommended for predictability and to avoid bugs
Exception: == can be used to check for null or undefined simultaneously

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.