1 /* 2 1. 浏览器在没有滚动条的时候，scrollLeft/scrollTop赋值后不会发生变化，始终是0； 3 2. scrollLeft，scrollTop为负数值时会报错 4 */ 5 var scroll = function (elm) { 6     var elms = elm ? [elm] : [document.documentElement, document.body], 7         scrollX = false, 8         scrollY = false, 9         i, len, tmp, obj;10 11     for (i = 0, len = elms.length; i < len; i++) {12         obj = elms[i];13 14         //Test horizontal scroll15         tmp = obj.scrollLeft;16         obj.scrollLeft += (tmp > 0) ? -1 : 1;17         obj.scrollLeft !== tmp && (scrollX = scrollX || true);18         obj.scrollLeft = tmp;19 20         //Test vertical scroll21         tmp = obj.scrollTop;22         obj.scrollTop += (tmp > 0) ? -1 : 1;23         obj.scrollTop !== tmp && (scrollY = scrollY || true);24         obj.scrollTop = tmp;25     }26 27     return {28         ‘isScrollX‘: scrollX,29             ‘isScrollY‘: scrollY30     };31 };

 1 /* 2 1. 向页面插入一个看不到的元素，并设置它的宽度w，自身显示滚动条； 3 2. 浏览器滚动条的宽度 = w - 它的clientWidth 4 */ 5 var getScrollWidth = function () { 6     var testNode, tmp; 7  8     testNode = document.createElement(‘div‘); 9     testNode.style.cssText = "position:absolute;width:50px;height:50px;top:-1000px;overflow-y:scroll;";10     document.body.appendChild(testNode);11 12     tmp = testNode.clientWidth;13     document.body.removeChild(testNode);14     return 50 - tmp;15 };