drag-scroll.js

var script = document.createElement('script');
script.type = 'text/javascript';
script.src = 'https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js';
document.head.appendChild(script);

var scrollX = 0;
var scrollY = 0;
var curYPos = 0;
var curXPos = 0;
var curDown = false;

$(document).on("mousemove", function (event) {
  if (curDown === true) {
    scrollX += (curXPos - event.pageX);
    scrollY += (curYPos - event.pageY);
    $(document).scrollTop(parseInt($(document).scrollTop() + (curYPos - event.pageY)));
    $(document).scrollLeft(parseInt($(document).scrollLeft() + (curXPos - event.pageX)));
  }
});

$(document).on("mousedown", function (e) {
  curDown = true;
  curYPos = e.pageY;
  curXPos = e.pageX;
  scrollX = 0;
  scrollY = 0;
  e.preventDefault();
  e.stopPropagation();
  e.stopImmediatePropagation();
  return false;
});

$(document).on("mouseup", function (e) {
  curDown = false;
  e.preventDefault();
  e.stopPropagation();
  e.stopImmediatePropagation();
  return false;
});

$(document).on("click", function (e) {
  var canClick = Math.abs(scrollX) < 5 && Math.abs(scrollY) < 5;
  console.log(scrollX, scrollY, canClick);
  if (!canClick) {
    e.preventDefault();
    e.stopPropagation();
    e.stopImmediatePropagation();
    return false;
  }
});

$(window).on("mouseup", function (e) {
  curDown = false;
  e.preventDefault();
  e.stopPropagation();
  e.stopImmediatePropagation();
  return false;
});