Generational Garbage Collection (JavaScript)

JavaScript engines use generational GC to optimize for short-lived objects.

Generations

• Young space: New allocations, collected frequently.
• Old space: Promoted objects that survive collections.

Why it matters

• Excess allocations in render loops increase GC pressure.
• Long-lived caches grow old space and cause longer pauses.

Practical guidance

• Reuse objects in hot loops.
• Avoid holding large arrays in global state without limits.
• Clear timers and listeners when components unmount.

Interview prompt

• Explain how you reduce GC pressure in UI rendering.