移动端使用localStorage缓存Js和css文的方法(web开发)
将jquery和公共样式缓存到localStorage,可以减少Http请求,从而优化页面加载时间,下面的代码可以实现此功能:
<script type="text/javascript"> //入口函数 if (window.localStorage) { initJs(); initCss("css", "/gfdzp201508257998/Turntable/Style/css_whir.css"); } else { addFile("/gfdzp201508257998/Turntable/Script/jquery-1.8.3.min.js", "js"); addFile("/gfdzp201508257998/Turntable/Script/whir.turntable.js", "js"); addFile("/gfdzp201508257998/Turntable/Style/css_whir.css", "css"); } //第一步:加载页面js:先加载jQuery后加载用户脚本 function initJs() { var name = "jquery"; var url = "/gfdzp201508257998/Turntable/Script/jquery-1.8.3.min.js"; var xhr; var js = window.localStorage ? localStorage.getItem(name) : ""; if (js == null || js.length == 0) { if (window.ActiveXObject) { xhr = new ActiveXObject("Microsoft.XMLHTTP"); } else if (window.XMLHttpRequest) { xhr = new XMLHttpRequest(); } xhr.open("GET", url); xhr.send(null); xhr.onreadystatechange = function () { if (xhr.readyState == 4 && xhr.status == 200) { js = xhr.responseText; localStorage.setItem(name, js); js = js == null ? "" : js; addTxt(js, "js"); initTurntable(); //确保先引用Jquery } }; } else { addTxt(js, "js"); initTurntable(); } } //加载自定义脚本 function initTurntable() { var name = "turntable"; var url = "/gfdzp201508257998/Turntable/Script/whir.turntable.js"; var xhr; var js = window.localStorage ? localStorage.getItem(name) : ""; if (js == null || js.length == 0) { if (window.ActiveXObject) { xhr = new ActiveXObject("Microsoft.XMLHTTP"); } else if (window.XMLHttpRequest) { xhr = new XMLHttpRequest(); } xhr.open("GET", url); xhr.send(null); xhr.onreadystatechange = function () { if (xhr.readyState == 4 && xhr.status == 200) { js = xhr.responseText; localStorage.setItem(name, js); js = js == null ? "" : js; addTxt(js, "js"); } }; } else { addTxt(js, "js"); } } //第二步:初始化Css function initCss(name, url) { var xhr; var css = window.localStorage ? localStorage.getItem(name) : ""; if (css == null || css.length == 0) { if (window.ActiveXObject) { xhr = new ActiveXObject("Microsoft.XMLHTTP"); } else if (window.XMLHttpRequest) { xhr = new XMLHttpRequest(); } xhr.open("GET", url); xhr.send(null); xhr.onreadystatechange = function () { if (xhr.readyState == 4 && xhr.status == 200) { css = xhr.responseText; localStorage.setItem(name, css); css = css == null ? "" : css; css = css.replace(/images\//g, "style/images/"); addTxt(css, "css"); } }; } else { css = css.replace(/images\//g, "style/images/"); addTxt(css, "css"); } } //辅助方法1:动态添加js,css文件引用 function addFile(url, fileType) { var head = document.getElementsByTagName('HEAD').item(0); var link; if (fileType == "js") { link = document.createElement("script"); link.type = "text/javascript"; link.src = url; } else { link = document.createElement("link"); link.type = "text/css"; link.rel = "stylesheet"; link.rev = "stylesheet"; link.media = "screen"; link.href = url; } head.appendChild(link); } //辅助方法2:动态添加js,css文件内容 function addTxt(text, fileType) { var head = document.getElementsByTagName('HEAD').item(0); var link; if (fileType == "js") { link = document.createElement("script"); link.type = "text/javascript"; link.innerHTML = text; } else { link = document.createElement("style"); link.type = "text/css"; link.innerHTML = text; } head.appendChild(link); } </script>
查看写入记录:
封装成JS插件:
/** * 插件功能:使用localStorage缓存js和css文件,减少http请求和页面渲染时间,适用于Web移动端H5页面制作。 * 插件作者:zhangqs008@163.com * 使用方法: * 1.使用此插件前,需要给插件的pageVersion变量赋值,建议变量值由服务器后端输出,当需要更新客户端资源时,修改版本值即可。 * 2.加载Js:由于js加载有顺序要求,所以需要将后加载的脚本作为前一个脚本的回调参数传入,如: * whir.res.loadJs("jquery", "<%= BasePath %>Turntable/Script/jquery-1.8.3.min.js", * function () { * whir.res.loadJs("turntable", "Script/whir.turntable.js", null); * }); * 3.加载css,如:whir.res.loadCss("css", "/Style/css_whir.css", null); */ var whir = window.whir || {}; whir.res = { pageVersion: "", //页面版本,由页面输出,用于刷新localStorage缓存 //动态加载js文件并缓存 loadJs: function (name, url, callback) { if (window.localStorage) { var xhr; var js = localStorage.getItem(name); if (js == null || js.length == 0 || this.pageVersion != localStorage.getItem("version")) { if (window.ActiveXObject) { xhr = new ActiveXObject("Microsoft.XMLHTTP"); } else if (window.XMLHttpRequest) { xhr = new XMLHttpRequest(); } if (xhr != null) { xhr.open("GET", url); xhr.send(null); xhr.onreadystatechange = function () { if (xhr.readyState == 4 && xhr.status == 200) { js = xhr.responseText; localStorage.setItem(name, js); localStorage.setItem("version", whir.res.pageVersion); js = js == null ? "" : js; whir.res.writeJs(js); if (callback != null) { callback(); //回调,执行下一个引用 } } }; } } else { whir.res.writeJs(js); if (callback != null) { callback(); //回调,执行下一个引用 } } } else { whir.res.linkJs(url); } }, loadCss: function (name, url) { if (window.localStorage) { var xhr; var css = localStorage.getItem(name); if (css == null || css.length == 0 || this.pageVersion != localStorage.getItem("version")) { if (window.ActiveXObject) { xhr = new ActiveXObject("Microsoft.XMLHTTP"); } else if (window.XMLHttpRequest) { xhr = new XMLHttpRequest(); } if (xhr != null) { xhr.open("GET", url); xhr.send(null); xhr.onreadystatechange = function () { if (xhr.readyState == 4 && xhr.status == 200) { css = xhr.responseText; localStorage.setItem(name, css); localStorage.setItem("version", whir.res.pageVersion); css = css == null ? "" : css; css = css.replace(/images\//g, "style/images/"); //css里的图片路径需单独处理 whir.res.writeCss(css); } }; } } else { css = css.replace(/images\//g, "style/images/"); //css里的图片路径需单独处理 whir.res.writeCss(css); } } else { whir.res.linkCss(url); } }, //往页面写入js脚本 writeJs: function (text) { var head = document.getElementsByTagName('HEAD').item(0); var link = document.createElement("script"); link.type = "text/javascript"; link.innerHTML = text; head.appendChild(link); }, //往页面写入css样式 writeCss: function (text) { var head = document.getElementsByTagName('HEAD').item(0); var link = document.createElement("style"); link.type = "text/css"; link.innerHTML = text; head.appendChild(link); }, //往页面引入js脚本 linkJs: function (url) { var head = document.getElementsByTagName('HEAD').item(0); var link = document.createElement("script"); link.type = "text/javascript"; link.src = url; head.appendChild(link); }, //往页面引入css样式 linkCss: function (url) { var head = document.getElementsByTagName('HEAD').item(0); var link = document.createElement("link"); link.type = "text/css"; link.rel = "stylesheet"; link.rev = "stylesheet"; link.media = "screen"; link.href = url; head.appendChild(link); } }
调用该插件:
<script type="text/javascript"> //入口函数 whir.res.pageVersion = "1002"; //页面版本,用于检测是否需要更新缓存 whir.res.loadJs("jquery", "/gfdzp201508257998/Turntable/Script/jquery-1.8.3.min.js", function () { whir.res.loadJs("turntable", "/gfdzp201508257998/Turntable/Script/whir.turntable.js", null); }); whir.res.loadCss("css", "/gfdzp201508257998/Turntable/Style/css_whir.css", null); </script>
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