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移动端使用localStorage缓存Js和css文的方法(web开发)

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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>

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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