How does JavaScript handle memory leaks and how can you avoid them?

Question

How does JavaScript handle memory leaks and how can you avoid them?

Answer

A memory leak happens when objects that are no longer needed remain in memory due to lingering references.

Common causes:

• Unremoved event listeners
• Global variables
• Forgotten timers or intervals
• Closures keeping references alive

let cache = {};
function storeData(key, value) {
  cache[key] = value;
}

If never cleared, this cache keeps growing — leaking memory.

Prevention Tips

• Remove event listeners on component unmount
• Clear timeouts/intervals
• Use weak references (WeakMap)
• Monitor via Chrome DevTools → Performance → Memory

Quick Practice

Create an example where a DOM event listener leaks memory and fix it properly.

Summary

Memory leaks silently degrade performance — be mindful of what you retain.