JS实现多个下拉框值拼接至文本框的示例

<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
<script language="javascript">
function doit(ofrm){
//ofrm.t1.value=parseInt(ofrm.s1.value)+parseInt(ofrm.s2.value)+parseInt(ofrm.s3.value)+parseInt(ofrm.s4.value);
ofrm.t1.value=ofrm.s1.value+ofrm.s2.value+ofrm.s3.value+ofrm.s4.value;
} 
</script>
</HEAD>
<BODY>
<form name="tfrm">
<select name="s1" onChange="javascript:doit(this.form);">
<option value="*" selected>请选择</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
<select name="s2" onChange="javascript:doit(this.form);">
<option value="*" selected>请选择</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
<select name="s3" onChange="javascript:doit(this.form);">
<option value="*" selected>请选择</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
<select name="s4" onChange="javascript:doit(this.form);">
<option value="*" selected>请选择</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
<input type="text" name="t1" value="">
</form>
</BODY>
</HTML>