动态增加一个层的宽度

var div1 = document.getElementById("div1"); var oldwidth = div1.style.width; oldwidth = parseInt(oldwidth, 10) + 50 + "px"; div1.style.width = oldwidth;

网页内容：

<div id="div1" style="width:200px;height:200px;border:1px solid #000;"></div> <input type="button" value="大小增加50" onclick="increase()" />