Source
<HTML>
<BODY OnLoad="document.Form1.msgBox.value=msg[0];">
<SCRIPT Language="JavaScript">
   msg = new Array(3);
   msg[0] = "在某一個物件按下滑鼠時,\r\n即發生此一事件,\r\n例如在按鈕上按下滑鼠。"
   msg[1] = "當輸入游標移到某一個物件時,\r\n該物件即發生此一事件。"
   msg[2] = "當輸入游標從某一個物件離開時,\r\n該物件即發生此一事件。"

   function ChangeMsg() {
      i = document.Form1.topic.selectedIndex;
      document.Form1.msgBox.value = msg[i];
   }
</SCRIPT>
<FORM Name=Form1>
<SELECT Name=topic OnChange="ChangeMsg();">
   <OPTION Value="0">OnClick
   <OPTION Value="1">OnFocus
   <Option Value="2">OnBlur
</SELECT><P>
<TEXTAREA Name=msgBox Rows=5 Cols=60></TEXTAREA>
</FORM>

</BODY>