JavaScript Performance – Profiling & Optimisation

Key performance tips:

• Minimise reflows – batch DOM reads/writes.
• Use requestAnimationFrame for UI updates.
• Leverage Web Workers for heavy computation off the main thread.
• Avoid memory leaks – clear timers, remove listeners, null out references.
• Use performance.now() for high‑resolution timing.

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Example: Debounce a resize handler

function debounce(fn, delay){
  let id;
  return (...args)=>{
    clearTimeout(id);
    id = setTimeout(()=>fn.apply(this,args), delay);
  };
}
window.addEventListener('resize', debounce(()=>{
  console.log('Resized', window.innerWidth);
},200));