enable-disable-scroll.js

// doesn't work with ios, but works with everything else.
var keys = {
          37: 1,
          38: 1,
          39: 1,
          40: 1
        },

        preventDefault = function (e) {
          e = e || window.event;
          if (e.preventDefault) e.preventDefault();
          e.returnValue = false;
        },

        preventDefaultForScrollKeys = function(e) {
          if (keys[e.keyCode]) {
            preventDefault(e);
            return false;
          }
        },

    // Disables scroll events
    var disableScroll = function () {
      if (window.addEventListener) // older FF
        window.addEventListener('DOMMouseScroll', preventDefault, false);
      window.onwheel = preventDefault; // modern standard
      window.onmousewheel = document.onmousewheel = preventDefault; // older browsers, IE
      window.ontouchmove = preventDefault; // mobile
      document.onkeydown = preventDefaultForScrollKeys;
    },

    // Enables scroll events
    enableScroll = function () {
      if (window.removeEventListener) window.removeEventListener('DOMMouseScroll', preventDefault, false);
      window.onmousewheel = document.onmousewheel = null;
      window.onwheel = null;
      window.ontouchmove = null;
      document.onkeydown = null;
    };


// anaother approach - works with ios
  function disableScroll(){
    document.body.addEventListener('touchmove', preventDefault, { passive: false });
  }
  function enableScroll(){
    document.body.removeEventListener('touchmove', preventDefault, { passive: false });
  }