What is the difference between === and ==?
=== compares without coercion, requiring same type and value. == compares with coercion, converting types before comparing. Always use === to avoid unexpected type conversions.
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More FAQs in A JavaScript Interview Cheat Sheet of Must-Know Topics
let/const/var, hoisting and the temporal dead zone, closures, this, the event loop, promises, async/await, prototypes, equality (=== vs ==), and DOM events including event delegation and bubbling. Each is common in JS interviews.
Single-threaded JS handles async via the call stack, the microtask queue (promises), and the macrotask queue (setTimeout, events). Microtasks run before macrotasks, which is why promise callbacks run before setTimeout callbacks set at the same time.
Functions that remember their lexical scope, even after the outer function has returned. They enable data privacy, callbacks, and patterns like once and memoize.
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