How do you pass arguments to a setTimeout callback in JavaScript?
Use extra arguments after the delay: setTimeout(fn, 1000, arg1, arg2). Or use an arrow function: setTimeout(() => fn(arg1, arg2), 1000). Do not call the function directly: setTimeout(fn(arg1), 1000) calls fn immediately.
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More FAQs in setTimeout Best Practices in Modern JavaScript
Do not rely on exact timing, always clear timers, use let in loops, bind this for method callbacks, pass functions (not results), use requestAnimationFrame for animations, break long tasks into chunks, and use Web Workers for heavy computation.
Always store the timer ID and call clearTimeout when the timer is no longer needed. In React, clean up in useEffect: return () => clearTimeout(id). Never leave a timer running after a component unmounts.
No. Use requestAnimationFrame instead. It syncs with the browser's refresh rate (usually 60fps), runs before the next paint, and produces smoother animations than setTimeout.
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