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移動端使用localStorage緩存Js和css文的方法(web開發(fā))

更新時間：2016年09月20日 09:54:44 作者：清山博客

這篇文章主要介紹了web移動端使用localStorage緩存Js和css文的方法,非常不錯，具有參考借鑒價值，需要的朋友可以參考下

將jquery和公共樣式緩存到localStorage，可以減少Http請求，從而優(yōu)化頁面加載時間，下面的代碼可以實現(xiàn)此功能：

<script type="text/javascript"> 
//入口函數(shù) 
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：加載頁面js：先加載jQuery后加載用戶腳本 
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(); //確保先引用Jquery 
} 
}; 
} else { 
addTxt(js, "js"); 
initTurntable(); 
} 
} 
//加載自定義腳本 
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"); 
} 
} 
//輔助方法1：動態(tài)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); 
} 
//輔助方法2：動態(tài)添加js，css文件內(nèi)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>

查看寫入記錄：

封裝成JS插件：

/** 
* 插件功能：使用localStorage緩存js和css文件，減少http請求和頁面渲染時間，適用于Web移動端H5頁面制作。 
* 插件作者：zhangqs008@163.com 
* 使用方法： 
* 1.使用此插件前，需要給插件的pageVersion變量賦值，建議變量值由服務(wù)器后端輸出，當(dāng)需要更新客戶端資源時，修改版本值即可。 
* 2.加載Js：由于js加載有順序要求，所以需要將后加載的腳本作為前一個腳本的回調(diào)參數(shù)傳入，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.加載css，如：whir.res.loadCss("css", "/Style/css_whir.css", null); 
*/ 
var whir = window.whir || {}; 
whir.res = { 
pageVersion: "", //頁面版本，由頁面輸出，用于刷新localStorage緩存 
//動態(tài)加載js文件并緩存 
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(); //回調(diào)，執(zhí)行下一個引用 
} 
} 
}; 
} 
} else { 
whir.res.writeJs(js); 
if (callback != null) { 
callback(); //回調(diào)，執(zhí)行下一個引用 
} 
} 
} 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里的圖片路徑需單獨處理 
whir.res.writeCss(css); 
} 
}; 
} 
} else { 
css = css.replace(/images\//g, "style/images/"); //css里的圖片路徑需單獨處理 
whir.res.writeCss(css); 
} 
} else { 
whir.res.linkCss(url); 
} 
}, 
//往頁面寫入js腳本 
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); 
}, 
//往頁面寫入css樣式 
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); 
}, 
//往頁面引入js腳本 
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); 
}, 
//往頁面引入css樣式 
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); 
} 
}

調(diào)用該插件：

<script type="text/javascript"> 
//入口函數(shù) 
whir.res.pageVersion = "1002"; //頁面版本，用于檢測是否需要更新緩存 
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>

以上所述是小編給大家介紹的移動端使用localStorage緩存Js和css文的方法(web開發(fā))，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復(fù)大家的。在此也非常感謝大家對腳本之家網(wǎng)站的支持！

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