工具函数之JS

 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 scroll
15         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 scroll
21         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‘: scrollY
30     };
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 };