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JavaScript Academy · Lesson

Avoiding leaks — closures, timers, references

Prevent memory leaks by clearing timers, limiting closures, and dropping unused references; use tiny patterns that beginners can apply.

What is a leak?

Goal: Avoid simple leaks.

  • Always clear timers
  • Do not keep unused references
  • Keep closures small
  • Prefer short-lived data
Avoiding leaks — closures, timers, references — illustration 1

Clear intervals

Keep the interval id; call clearInterval during cleanup so the timer and its captures can be collected.

// Start an interval and then clear it to avoid leaks
function startTicker() {
  // store id so we can clear later
  const id = setInterval(function () {
    // work would run every X ms; omitted for demo
  }, 1000);

  // simulate screen close / cleanup
  clearInterval(id);
  console.log("interval cleared");
}

startTicker();
Avoiding leaks — closures, timers, references — illustration 2

All lessons in this course

  1. Big-O basics, hot vs cold paths (beginner wins)
  2. Avoiding leaks — closures, timers, references
  3. Profiling intro (Node/DevTools) — tiny timing habits
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