This limits the rate at which a function can fire, for optimized performance.

debounce.js

function debounce(func, wait, immediate) {
  let timeout;
  return function() {
    const context = this, args = arguments;
    const later = function() {
      timeout = null;
      if (!immediate) {
        func.apply(context, args);
      }
    };
    const callNow = immediate && !timeout;
    clearTimeout(timeout);
    timeout = setTimeout(later, wait);
    if (callNow) {
      func.apply(context, args);
    }
  };
}