用prototype.js怎片被的事件？
<img id= "arrow " src= "select_arrow.gif " width= "15 " height= "18 " />

怎用prototype.js展的或事件：
$( "arrow ")被行自定函a()？

[解决办法]
<script language= "javascript ">
Event.observe($( 'arrow '), 'click ', function(event) {
alert( 'a ');
});
</script>