W3School TIY
编辑您的代码：
<html> <head> <script type="text/javascript"> function bgChange(bg) { document.getElementById('x').style.background="url(" + bg + ")" } </script> </head> <body> <p>本例演示如何向按钮插入背景图像。</p> <p>请把鼠标移动到图像上，按钮会获得一幅背景图像：</p> <table width="300" height="100"> <tr> <td onmouseover="bgChange('../i/eg_bg_03.gif'/*tpa=http://www.jb51.net/i/eg_bg_03.gif*/)" background="../i/eg_bg_03.gif"> </td> <td onmouseover="bgChange('../i/eg_bg_04.gif'/*tpa=http://www.jb51.net/i/eg_bg_04.gif*/)" background="../i/eg_bg_04.gif"> </td> </tr> </table> <form> <input id="x" type="button" value="Mouse over the images"> </form> </body> </html>
查看结果: