FrontendHaltJavaScript·Intermediate·Conceptual·1 min read
Why is null == undefined true but null == 0 false?
Short interview answer
The abstract equality algorithm specifically defines null and undefined as loosely equal only to each other and to themselves — they are deliberately excluded from the numeric coercion path that would otherwise compare them to 0.
Key takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.