<select name="A">
<option value="">请选择</select>
<option value="1">a1</select>
<option value="2">a2</select>
<option value="3">a3</select>
</select>
<select name="A1">
<option value="">请选择</select>
<option value="1">a1</select>
<option value="2">a2</select>
<option value="3">a3</select>
</select>
<select name="A2">
<option value="">请选择</select>
<option value="1">a1</select>
<option value="2">a2</select>
<option value="3">a3</select>
</select>
当在"A"里选择a1时,A1和A2都选择a1.
当在"A"里选择a2时,A1和A2同时选择a2.
如何做?
<option value="">请选择</select>
<option value="1">a1</select>
<option value="2">a2</select>
<option value="3">a3</select>
</select>
<select name="A1">
<option value="">请选择</select>
<option value="1">a1</select>
<option value="2">a2</select>
<option value="3">a3</select>
</select>
<select name="A2">
<option value="">请选择</select>
<option value="1">a1</select>
<option value="2">a2</select>
<option value="3">a3</select>
</select>
当在"A"里选择a1时,A1和A2都选择a1.
当在"A"里选择a2时,A1和A2同时选择a2.
如何做?
<option value="">请选择 </option>
<option value="1">a1 </option>
<option value="2">a2 </option>
<option value="3">a3 </option>
</select>
<select name="A1">
<option value="">请选择 </option>
<option value="1">a1 </option>
<option value="2">a2 </option>
<option value="3">a3 </option>
</select>
<select name="A2">
<option value="">请选择 </option>
<option value="1">a1 </option>
<option value="2">a2 </option>
<option value="3">a3 </option>
</select>
<select name="A" onchange="A1.value=A2.value=this.value">
<option value="">请选择 </option>
<option value="1">a1 </option>
<option value="2">a2 </option>
<option value="3">a3 </option>
</select>
<select name="A1">
<option value="">请选择 </option>
<option value="1">a1 </option>
<option value="2">a2 </option>
<option value="3">a3 </option>
</select>
<select name="A2">
<option value="">请选择 </option>
<option value="1">a1 </option>
<option value="2">a2 </option>
<option value="3">a3 </option>
</select>
<head>
<title>下拉菜单事件</title>
</head>
<body>
<select name="A" onchange="A1.value=A2.value=this.value">
<option value="">请选择 </option>
<option value="1">a1 </option>
<option value="2">a2 </option>
<option value="3">a3 </option>
</select>
<select name="A1">
<option value="">请选择 </option>
<option value="1">a1 </option>
<option value="2">a2 </option>
<option value="3">a3 </option>
</select>
<select name="A2">
<option value="">请选择 </option>
<option value="1">a1 </option>
<option value="2">a2 </option>
<option value="3">a3 </option>
</select>
</body>
<html>