<html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"> <title></title> <style type="text/css"> .day { background-color:White; } .night { background-color:Black } </style> <script language="javascript" type="text/javascript"> function operStyle() { var divObj = document.getElementById("divContent"); var btnObj = document.getElementById("btnCommit"); if (divObj.className == "day") { divObj.className = "night"; btnObj.value = "開燈"; } else { divObj.className = "day"; btnObj.value = "關燈"; } } //批量修改div的樣式屬性，由多種樣式構成 //方法1： function methodOne() { var divObj = document.getElementById("divTest"); divObj.style.backgroundColor = "blue"; divObj.style.border = "solid 1px red"; divObj.style.width = "300px"; divObj.style.height = "200px"; divObj.style.backgroundPosition = "center"; } //方法2： function methodTwo() { var divObj = document.getElementById("divTest"); divObj.style.cssText = "background-color:Blue; border:solid 1px red; width:300px; height:200px; background-position:center"; } </script></head><body> <form id="form1" runat="server"> <div id="divContent" class="day"> <font color="red">我是一個div啊，咿呀咿呀呦！</font> </div> <input type="button" value="關燈" id="btnCommit" onclick="operStyle();" /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <hr /> <h1>修改divTest的樣式，多屬性操作</h1> <div id="divTest" > <font color="red">修改divTest的樣式</font> </div> <input type="button" value="修改divTest的樣式" onclick="methodTwo()" /> </form></body></html>
我們用js書寫css樣式通常會用下面的兩種方式：
一般情況下我們用js設定元素對象的樣式會使用這樣的形式：
複製代碼 代碼如下:
var element= document.getElementById(”id”);
element.style.width=”20px”;
element.style.height=”20px”;
element.style.border=”solid 1px red”;
但是上面的方法有一個缺點，樣式一多，代碼就很多；而且通過JS來覆寫對象的樣式是比較典型的一種銷毀原樣式並重建的過程，這種銷毀和重建，都會增加瀏覽器的開銷。
js中有一個cssText的方法：
文法為：obj.style.cssText(”樣式”)；
上面的代碼我們可以修改成：
複製代碼 代碼如下:
element.style.cssText=”width:20px;height:20px;border:solid 1px red;”;
這種寫法可以盡量避免頁面的多次reflow，提高頁面效能。
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