<form action="" id="form1">
<input type="submit" name="update" value="更新" onclick="setAction(1)">
<input type="submit" name="delete" value="删除" onclick="setAction(2)">
</action>

<script>
function setAction(type){
 if(type == 1){
    document.getElementById("form1").action = "a.do"
  }
 else if(type == 2){
    document.getElementById("form1").action = "b.do"
  }

}
</script>

------解决方案--------------------
3#楼是对的！可以按他的写
也可以这样，然后在action中进行处理
JScript code

<form action="" id="form1">
<input type="submit" name="update" value="更新" onclick="setAction('update')">
<input type="submit" name="delete" value="删除" onclick="setAction('delete')">
</action>

<script>
function setAction(typeName){
    document.getElementById("form1").action = "a.do?method=xxx&typeName="+typeName;
    document.action.submit();
}
</script>

------解决方案--------------------

<form action="" id="form1">
<input type="submit" name="update" value="更新" onclick="location.href='a.do'"/>
<input type="submit" name="delete" value="删除" onclick="location.href='b.do'"
/>