AlgoDaily - Implement Throttling - One Pager Cheat Sheet

One Pager Cheat Sheet

Throttling is a technique to limit the number of times a function can execute in any given interval, which is useful for cases like infinite scrolling where a function needs to be executed only once per user action.
By using a boolean flag like isThrottling and the setTimeout method, we can create a throttle function that executes a given function after a certain amount of time, and save any further calls with different arguments for later invocation.

This is our final solution.

To visualize the solution and step through the below code, click Visualize the Solution on the right-side menu or the VISUALIZE button in Interactive Mode.

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}
 
function throttle(func, waitTime) {
  // Set isThrottling flag to false to start
  // and savedArgs to null
  let isThrottling = false,
    savedArgs = null;
  // Spread the arguments for .apply
  return function (...args) {
    // Return a wrapped function
    // Flag preventing immediate execution
    if (!isThrottling) {
      // Actual initial function execution
      func.apply(this, args);
      // Flip flag to throttling state
      isThrottling = true;
      // Queue up timer to flip the flag so future iterations can occur
      function queueTimer() {
        setTimeout(() => {
          // Stop throttling
          isThrottling = false;
          // Queueing up the next invocation after wait time passes
          if (savedArgs) {
            func.apply(this, savedArgs);
            isThrottling = true;
            savedArgs = null;
            queueTimer();
          }
        }, waitTime);
      }
      queueTimer();
    }
    // Wait state until timeout is done
    // Save arguments

That's all we've got! Let's move on to the next tutorial.

If you had any problems with this tutorial, check out the main forum thread here.