FrontendHaltJavaScript·Intermediate·Conceptual·1 min read
What is a long task?
Short interview answer
In web performance tooling, a main-thread task exceeding 50 milliseconds is reported as a long task. The blocking portion beyond 50 milliseconds contributes to total blocking time.
Key takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.