javascript获取选中单选按钮radio的值

<th>性别:</th>
 <td>
  <input type="radio" id="male" value="男" name="gender"/>男
  <input type="radio" id="female" value="女" name="gender"/>女
 </td>
</tr>

<script type="text/javascript">
		window.onload = function(){
			var gender = '${user.gender}';
			if(gender === '男'){
				document.getElementById('male').checked = true;
			}else{
				document.getElementById('female').checked = true;
			}	
		}
	</script>