FrontendHaltJavaScript·Advanced·Coding·1 min read
Can closures cause memory leaks?
Short interview answer
A reachable closure keeps its referenced environment reachable. That is intentional, but retaining a long-lived callback can also retain large objects unnecessarily. Remove obsolete listeners and timers, and avoid capturing more state than the callback needs.
Example
function attach(node) { const big = new Array(1_000_000).fill('x'); // captured by `handler` const handler = () => console.log(big.length); node.addEventListener('click', handler); return () => node.removeEventListener('click', handler); // call on teardown}Key takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.