debouncing

debounce-proto.js

Function.prototype.debounce = function (delay) {
  var func = this, 
      timeout;
      
  return function debounced() {
    var obj = this, 
        args = arguments;
        
    function delayed () {
      func.apply(obj, args);
      timeout = null; 
    };

    if (timeout) clearTimeout(timeout);
    timeout = setTimeout(delayed, delay || 100); 
  }
}

simple-debouncing.js

var timeout;

function callback() {
  console.log(window.scrollY)
}

function delayCallback() {
  if(timeout)
    clearTimeout(timeout)
  
  timeout = window.setTimeout(callback, 100)
}

document.addEventListener('scroll', delayCallback)