Memory Allocation Example (JavaScript)

This example highlights how frequent allocations can impact performance and how to avoid them.

Scenario

You render a list of items every animation frame and create new arrays each time.

const renderFrame = (items: number[]) => {
  const doubled = items.map((item) => item * 2);
  draw(doubled);
};

Improvement

Reuse arrays when possible or move allocation outside hot loops.

const buffer: number[] = [];

const renderFrame = (items: number[]) => {
  buffer.length = 0;
  for (const item of items) buffer.push(item * 2);
  draw(buffer);
};

Takeaway

Minimize allocations in tight loops to reduce GC pressure and dropped frames.