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HTML
HTML由一些普通文本組成。如果服務(wù)器通過XMLHttpRequest發(fā)送HTML,文本將存儲(chǔ)在responseText屬性中。不必從responseText屬性中讀取數(shù)據(jù),它已經(jīng)是期望的格式,可以直接將其插入到頁面中。插入HTML代碼最簡單的方法是更新這個(gè)元素的innerTHML屬性。
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> <script type="text/javascript"> window.onload = function() { var aNodes = document.getElementsByTagName("a"); for (var i = 0; i < aNodes.length; i++) { aNodes[i].onclick = function() { var request = new XMLHttpRequest(); var method = "GET"; var url = this.href; request.open(method, url); request.send(null); request.onreadystatechange = function() { if (request.readyState == 4) { if (request.status == 200 || request.status == 304) { document.getElementById("details").innerHTML = request.responseText; } } } return false; } } } </script> </head> <body> <ul> <li><a href="a.html">百度</a></li> </ul> <div id="details"></div> </body> </html>
a.html
<a >http://www.baidu.com</a>
優(yōu)點(diǎn)
-從服務(wù)器端發(fā)送的HTML代碼在瀏覽器端不需要用Javascript進(jìn)行解析。
-HTML的可讀性好
-HTML代碼塊與innerHTML屬性搭配,效率高。
缺點(diǎn)
-若需要通過Ajax更新一篇文檔的多個(gè)部分,HTML不合適
-innerHTML不是DOM標(biāo)準(zhǔn)
XML
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> <script type="text/javascript"> window.onload = function() { var aNodes = document.getElementsByTagName("a"); for (var i = 0; i < aNodes.length; i++) { aNodes[i].onclick = function() { var request = new XMLHttpRequest(); var method = "GET"; var url = this.href; request.open(method, url); request.send(null); request.onreadystatechange = function() { if (request.readyState == 4) { if (request.status == 200 || request.status == 304) { //結(jié)果為XML格式,需要使用responseXML var result = request.responseXML; //結(jié)果不能直接用,必須先創(chuàng)建對應(yīng)的結(jié)點(diǎn),再把結(jié)點(diǎn)放入到details中 var name = result.getElementsByTagName("name")[0].firstChild.nodeValue; var website = result.getElementsByTagName("website")[0].firstChild.nodeValue; var email = result.getElementsByTagName("email")[0].firstChild.nodeValue; var aNode = document.createElement("a"); aNode.appendChild(document.createTextNode(name)); aNode.href = "mailto:" + email; var h3Node = document.createElement("h3"); h3Node.appendChild(aNode); var aNode2 = document.createElement("a"); aNode2.appendChild(document.createTextNode(name)); aNode2.href = website; var detailsNode = document.getElementById("details"); detailsNode.innerHTML = ""; detailsNode.appendChild(h3Node); detailsNode.appendChild(aNode2); } } } return false; } } } </script> </head> <body> <ul> <li><a href="andy.xml">andy</a></li> </ul> <div id="details"></div> </body> </html>
andy.xml
<?xml version="1.0" encoding="UTF-8"?> <details> <name>Andy Budd</name> <website>http://www.baidu.com</website> <email>umgsai@126.com</email> </details>
優(yōu)點(diǎn)
-XML是一種通用的數(shù)據(jù)格式
-不必把數(shù)據(jù)強(qiáng)加到已定義好的格式中,而是要為數(shù)據(jù)自定義合適的標(biāo)記
-利用DOM可以完全掌控文檔
缺點(diǎn)
-如果文檔來自服務(wù)器,就必須保證文檔含有正確的首部信息。若文檔類型不正確,那么responseXML的值將是空的
-當(dāng)瀏覽器接收到長的XML文件后,DOM解析可能會(huì)很復(fù)雜
JSON
JSON(JavaScript Object Notation)是一種簡單的數(shù)據(jù)格式,比XML更輕巧,是JavaScript原生格式,這意味著在JavaScript中處理JSON不需要任何特殊的API或工具包。
<script type="text/javascript"> var object = { "name" : "umgsai", "age" : 12, "address" : { "city" : "beijing", "school" : "ctgu" }, "teaching" : function() { alert("這是一個(gè)方法"); } }; alert(object.name); alert(object.age); alert(object.address.city); object.teaching(); /*將字符串當(dāng)做語句來執(zhí)行 var testStr = "alert('hello')"; eval(testStr); */ /* var jsonStr = "{'name':'umgsai'}"; var testObject = eval("("+jsonStr+")");//字符串轉(zhuǎn)成json對象 alert(testObject.name); */ </script>
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> <script type="text/javascript"> window.onload = function() { var aNodes = document.getElementsByTagName("a"); for (var i = 0; i < aNodes.length; i++) { aNodes[i].onclick = function() { var request = new XMLHttpRequest(); var method = "GET"; var url = this.href; request.open(method, url); request.send(null); request.onreadystatechange = function() { if (request.readyState == 4) { if (request.status == 200 || request.status == 304) { //使用json var result = request.responseText; var object = eval("("+result+")"); //結(jié)果不能直接用,必須先創(chuàng)建對應(yīng)的結(jié)點(diǎn),再把結(jié)點(diǎn)放入到details中 var name = object.person.name; var website = object.person.website; var email = object.person.email; var aNode = document.createElement("a"); aNode.appendChild(document.createTextNode(name)); aNode.href = "mailto:" + email; var h3Node = document.createElement("h3"); h3Node.appendChild(aNode); var aNode2 = document.createElement("a"); aNode2.appendChild(document.createTextNode(name)); aNode2.href = website; var detailsNode = document.getElementById("details"); detailsNode.innerHTML = ""; detailsNode.appendChild(h3Node); detailsNode.appendChild(aNode2); } } } return false; } } } </script> </head> <body> <ul> <li><a href="andy.json">andy</a></li> </ul> <div id="details"></div> </body> </html>
andy.json
{"person":{ "name":"umgsai", "website":"http://www.baidu.com", "email":"umgsai@126.com" } }
優(yōu)點(diǎn)
-作為一種數(shù)據(jù)傳輸格式,json與xml很相似,但是json更加靈巧。
-json不需要從服務(wù)器端發(fā)送含有特定內(nèi)容類型的首部信息
缺點(diǎn)
-語法過于嚴(yán)謹(jǐn)
-代碼不易讀
-eval函數(shù)存在風(fēng)險(xiǎn)
小結(jié)
-若應(yīng)用程序不需要與其他應(yīng)用程序共享數(shù)據(jù)的時(shí)候,使用HTML片段來返回?cái)?shù)據(jù)是最簡單的。
-如果數(shù)據(jù)需要重用,JSON文件是個(gè)不錯(cuò)的選擇,其在性能和大小方面有優(yōu)勢。
-當(dāng)遠(yuǎn)程應(yīng)用程序未知時(shí),XML文檔是首選,因?yàn)閄ML是web服務(wù)領(lǐng)域的“世界語”
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