Implement throttle(func, wait, {leading, trailing})

Question

Accepted Answer

**Approach:** Track `lastCall` time + trailing timer. Leading invokes immediately if elapsed >= wait; trailing schedules last args.

```javascript
function throttle(func, wait, { leading = true, trailing = true } = {}) {
  let lastCall = 0, timer = null, lastArgs, lastThis, result;
  function invoke(time) {
    lastCall = time;
    result = func.apply(lastThis, lastArgs);
    lastArgs = lastThis = null;
    return result;
  }
  function throttled(...args) {
    const now = Date.now();
    const remaining = wait - (now - lastCall);
    lastArgs = args; lastThis = this;
    if (remaining <= 0 || remaining > wait) {
      if (timer) { clearTimeout(timer); timer = null; }
      if (leading) return invoke(now);
    }
    if (!timer && trailing) {
      timer = setTimeout(() => {
        timer = null;
        if (trailing && lastArgs) invoke(Date.now());
      }, remaining > 0 ? remaining : wait);
    }
    return result;
  }
  throttled.cancel = () => { clearTimeout(timer); timer = null; la

Implement throttle(func, wait, {leading, trailing})

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