代码如下：
<script type="text/javascript">
$(document).ready(function(){
$("input[id^='buttonValidate']").click(function(){ //当点击所有的id中包含'buttonValidate'的input标签时，执行函数
var btnVal=$.trim($(this).val());//trim函数，去掉空格
var str = $('#textareaValidate').val() + btnVal;//
$('#textareaValidate').val(str);//
});
});
</script>
<title>Insert title here</title>
</head>
<body>
<form id="form1" name="form1" action="" method="post">
<table id ="table1" class="base_table" cellspacing="0" border="1" style="border-collapse: collapse">
<tr>
<td >
<textarea cols="75" rows="5" id="textareaValidate"></textarea>
</td>
</tr>
<tr id="tr1">
<td>
<input id="buttonValidate1" type="button" value=" + "/>
<input id="buttonValidate2" type="button" value=" - "/>
<input id="buttonValidate3" type="button" value=" * "/>
<input id="buttonValidate4" type="button" value=" / "/>
<input id="buttonValidate5" type="button" value=" ! "/>
<input id="buttonValidate6" type="button" value=" = "/>
<input id="buttonValidate7" type="button" value=" < "/>
<input id="buttonValidate8" type="button" value=" > "/>
<input id="buttonValidate9" type="button" value=" & "/>
<input id="buttonValidate10" type="button" value=" | "/>
<input id="buttonValidate11" type="button" value=" ( "/>
<input id="buttonValidate12" type="button" value=" ) "/>
</td>
</tr>
</table>
</form>
</body>
</html>
以上实现的功能：点击+，则把+添加到textarea中，点击-，则把-添加到textarea中；
如图：