<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title></title> <style type="text/css"> * { margin: 0; padding: 0; font-family: "Helvetica Neue", Helvetica, Arial, STHeiti, "Microsoft Yahei", sans-serif; font-size: 14px; } html, body { width: 100%; height: 500%; background: -webkit-linear-gradient(top, #11c900, lightblue, lightcoral, lightcyan, lightgoldenrodyellow, lightgreen, lightpink, lightsalmon, lightseagreen); background: linear-gradient(top, #11c900, lightblue, lightcoral, lightcyan, lightgoldenrodyellow, lightgreen, lightpink, lightsalmon, lightseagreen); } a { text-decoration: none; color: #00516e; } a:hover, a:active, a:visited, a:target { color: #00516e; } #goLink { position: fixed; bottom: 100px; right: 100px; width: 50px; height: 50px; background-color: red; line-height: 50px; text-align: center; border-radius: 50%; opacity: .4; display: none; } #goLink:hover { opacity: 1; } </style> </head> <body> <a href="javascript:;" id="goLink">GO</a> <script src="utils.js"></script> <script type="text/javascript"> var goLink = document.getElementById('goLink'); window.onscroll = computed; goLink.onclick = function () { window.onscroll = null; this.style.display = 'none'; var timer = window.setInterval(function () { var curScrollTop = utils.win('scrollTop'); if (curScrollTop === 0) { window.clearInterval(timer); window.onscroll = computed; } curScrollTop -= curScrollTop / 10; utils.win('scrollTop', curScrollTop); console.log('ok'); }, 10); }; function computed() { var curTop = utils.win('scrollTop'),wHeight = utils.win('clientHeight'); goLink.style.display = curTop > wHeight ? 'block' : 'none'; } </script> </body> </html>
附：utils.js代码文件
'use strict'; var utils = (function () { var isSupport = 'getComputedStyle' in window; /* * toArray：Converts an array of classes to an array * @parameter： * likeAry[object]：Class array to convert * @return： * ary[Array]：Convert completed array * By Team on 2017-04-16 12:44 */ function toArray(likeAry) { var ary = []; try { ary = Array.prototype.slice.call(likeAry); } catch (e) { for (var i = 0, len = likeAry.length; i < len; i++) { ary[ary.length] = likeAry[i]; } } return ary; } /* * toJSON：Convert JSON string to JSON object * @parameter： * str[String]：JSON string * @return： * obj[Object]：JSON object * By Team on 2017-04-16 12:48 */ function toJSON(str) { return 'JSON' in window ? JSON.parse(str) : eval('(' + str + ')'); } /* * win：Operating browser box model information */ function win(attr, value) { if (typeof value === "undefined") { return document.documentElement[attr] || document.body[attr]; } document.documentElement[attr] = value; document.body[attr] = value; } /* * getCss：Gets the value of the specific style property for the current element * @parameter： * curEle[object]：current element * attr[string]：style properties of elements * @return： * Style attribute values for elements * By Team on 2017-04-23 12:29 */ function getCss(curEle, attr) { var val = null, reg = null; if (isSupport) { val = window.getComputedStyle(curEle, null)[attr]; } else { //->IE6~8 switch (attr) { case 'filter': case 'opacity': val = curEle.currentStyle['filter']; reg = /alpha(opacity=(.+))/i; val = reg.test(val) ? RegExp.$1 / 100 : 1; break; default: val = curEle.currentStyle[attr]; } } reg = /^-?d+(.d+)?(px|rem|em|pt)?$/i; val = reg.test(val) ? parseFloat(val) : val; return val; } /* * getCss：Set the style property value for an element，Setting inline styles for elements * @parameter： * curEle[object]：current element * attr[string]：style properties of elements * value：set style property value * By Team on 2017-04-23 15:36 */ function setCss(curEle, attr, value) { if (attr === 'float') { curEle['style']['cssFloat'] = value; curEle['style']['styleFloat'] = value; return; } if (attr === 'opacity') { curEle['style']['opacity'] = value; curEle['style']['filter'] = 'alpha(opacity=' + value * 100 + ')'; return; } var reg = /^(?:width|height|(?:(?:margin|padding)?(?:top|left|right|bottom)))$/i; if (reg.test(attr)) { !isNaN(value) ? value += 'px' : null; } curEle['style'][attr] = value; } /* * setGroupCss：Set the style attribute value for the batch * @parameter： * curEle[object]：current element * styleCollection[object]：style collection * By Team on 2017-04-23 15:36 */ function setGroupCss(curEle, styleCollection) { for (var key in styleCollection) { if (styleCollection.hasOwnProperty(key)) { setCss(curEle, key, styleCollection[key]); } } } /* * css：The style properties of the operating element, including the capture style, the individual settings style, and the batch settings style * @parameter： * curEle[object]：current element * By Team on 2017-04-23 15:36 */ function css() { var arg = arguments; if (arg.length >= 3) { //->SET CSS setCss.apply(this, arg); return; } if (arg.length === 2 && typeof arg[1] === 'object') { //->SET GROUP CSS setGroupCss.apply(this, arg); return; } return getCss.apply(this, arg); } /* * offset：Gets the offset of the current element distance BODY * @parameter： * curEle[object]：current element * @return： * [object]：{top:xxx,left:xxx} * By Team on 2017-04-23 16:43 */ function offset(curEle) { var l = curEle.offsetLeft, t = curEle.offsetTop, p = curEle.offsetParent; while (p) { if (navigator.userAgent.indexOf('MSIE 8') === -1) { l += p.clientLeft; t += p.clientTop; } l += p.offsetLeft; t += p.offsetTop; p = p.offsetParent; } return {top: t, left: l}; } /* * hasClass：Verify that the current element contains a single style class name * @parameter： * curEle[object]：current element * cName[string]：class name to validate * @return： * [boolean]：true/false * By Team on 2017-04-29 11:16 */ function hasClass(curEle, cName) { return new RegExp('(^| +)' + cName + '( +|$)').test(curEle.className); } /* * hasClass：Adds a class name to the current element * @parameter： * curEle[object]：current element * strClass[string]：Need to increase the style class name, can be more than, for example:'xxx','xxx xxx', ' xxx xxx '... * By Team on 2017-04-29 11:28 */ function addClass(curEle, strClass) { strClass = strClass.replace(/(^ +| +$)/g, '').split(/ +/g); for (var i = 0; i < strClass.length; i++) { var curClass = strClass[i]; if (!hasClass(curEle, curClass)) { curEle.className += ' ' + curClass; } } } /* * removeClass：Remove a class name to the current element * @parameter： * curEle[object]：current element * strClass[string]：Need to deleted the style class name, can be more than, for example:'xxx','xxx xxx', ' xxx xxx '... * By Team on 2017-04-29 11:44 */ function removeClass(curEle, strClass) { strClass = strClass.replace(/(^ +| +$)/g, '').split(/ +/g); for (var i = 0; i < strClass.length; i++) { var curClass = strClass[i], reg = new RegExp('(^| )' + curClass + '( |$)', 'g'); hasClass(curEle, curClass) ? curEle.className = curEle.className.replace(/ /g, ' ').replace(reg, ' ') : null; } curEle.className = curEle.className.replace(/(^ +| +$)/g, ''); } /* * toggleClass：If the passing style class name exists in the element, the delete operation is an operation * @parameter： * curEle[object]：current element * strClass[string]：class name to be operated * By Team on 2017-04-29 12:00 */ function toggleClass(curEle, strClass) { strClass = strClass.replace(/(^ +| +$)/g, '').split(/ +/g); for (var i = 0; i < strClass.length; i++) { var curClass = strClass[i]; hasClass(curEle, curClass) ? removeClass(curEle, curClass) : addClass(curEle, curClass); } } /* * byClass：Gets a set of elements by the element's style class，Compatible IE low version browser * @parameter： * strClass[string]：class name to be operated * context[HTMLElementObject]：get the range, the default is document * @return： * [Array]：All matching results * By Team on 2017-04-29 12:56 */ function byClass(strClass, context) { context = context || document; if (isSupport) { return toArray(context.getElementsByClassName(strClass)); } //->IE6~8 var allList = context.getElementsByTagName('*'), ary = [], reg = null; strClass = strClass.replace(/(^ +| +$)/g, '') .replace(/ +/g, '@@') .replace(/(?:^|@)([w-]+)(?:@|$)/g, '(?=.*(^| +)$1( +|$).*)'); reg = new RegExp(strClass); for (i = 0; i < allList.length; i++) { var cur = allList[i]; reg.test(cur.className) ? ary[ary.length] = cur : null; } return ary; } /* * children：Gets all the child nodes of the current container (element), which is filtered in all child elements, and specifies the name of the tag * @parameter * curEle[HTMLElement]：current element * tagName[string]：tag name * @return * [array]：Collection of elements */ function children(curEle, tagName) { var allNodes = curEle.childNodes, elementAry = []; for (var i = 0; i < allNodes.length; i++) { var curNode = allNodes[i]; if (curNode.nodeType === 1) { var curNodeTag = curNode.tagName.toUpperCase(); if (typeof tagName !== 'undefined') { tagName = tagName.toUpperCase(); curNodeTag === tagName ? elementAry[elementAry.length] = curNode : null; continue; } elementAry[elementAry.length] = curNode; } } return elementAry; } /* * prev：Get older brother element node */ function prev(curEle) { if (isSupport) { return curEle.previousElementSibling; } var p = curEle.previousSibling; while (p && p.nodeType !== 1) { p = p.previousSibling; } return p; } /* * prevAll：Get all brother element node */ function prevAll(curEle) { var ary = [], p = prev(curEle); while (p) { ary.unshift(p); p = prev(p); } return ary; } /* * next：Get next brother element node */ function next(curEle) { if (isSupport) { return curEle.nextElementSibling; } var n = curEle.nextSibling; while (n && n.nodeType !== 1) { n = n.nextSibling; } return n; } /* * nextAll：Get all brother element node */ function nextAll(curEle) { var ary = [], n = next(curEle); while (n) { ary.push(n); n = next(n); } return ary; } /* * siblings：Get all sibling element nodes */ function siblings(curEle) { return prevAll(curEle).concat(nextAll(curEle)); } /* * index：Gets the index of the current element */ function index(curEle) { return prevAll(curEle).length; } /* * firstChild：Gets the first child element in the container */ function firstChild(curEle) { if (isSupport) { return curEle.firstElementChild; } var first = curEle.firstChild; while (first && first.nodeType !== 1) { first = first.nextSibling; } return first; } /* * lastChild：Gets the last child element in the container */ function lastChild(curEle) { if (isSupport) { return curEle.lastElementChild; } var last = curEle.lastChild; while (last && last.nodeType !== 1) { last = last.previousSibling; } return last; } /* * prepend：Add a new element to the location of the specified container * @parameter * newEle：Newly added elements * container：Specified container */ function prepend(newEle, container) { var first = firstChild(container); if (first) { container.insertBefore(newEle, first); return; } container.appendChild(newEle); } /* * insertAfter：Add a new element to the old element * @parameter * newEle：New elements * oldEle：Original element */ function insertAfter(newEle, oldEle) { var n = next(oldEle), p = oldEle.parentNode; if (n) { p.insertBefore(newEle, n); return; } p.appendChild(newEle); } return { /*--TOOL--*/ toArray: toArray, toJSON: toJSON, win: win, /*--CSS OR STYLE--*/ offset: offset, css: css, hasClass: hasClass, addClass: addClass, removeClass: removeClass, toggleClass: toggleClass, /*--GET ELEMENTS--*/ byClass: byClass, children: children, prev: prev, next: next, prevAll: prevAll, nextAll: nextAll, siblings: siblings, index: index, firstChild: firstChild, lastChild: lastChild, /*--OPERATING ELEMENT--*/ insertAfter: insertAfter, prepend: prepend } })();