JavaScript控制表单元素操作实例：单选、复选与下拉菜单

鼠标悬停自动选中文本

1.鼠标悬停时自动选中文本

鼠标划过自动选中：<input type="text" value="默认值" onMouseOver="this.focus();" onfucus="this.seelct()" />

单选按钮的值获取与设置

2.配置单选按钮

代码：

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<title>js操作表单</title>
<script language="javascript">
function getChoice(){
var oForm=document.forms["myForm1"];
var aChoice=oForm.camera;
for(i=0;i<aChoice.length;i++)
if(aChoice[i].checked)
break;
alert("您使用的相机品牌是："+aChoice[i].value);
}
function setChoice(iNum){
var oForm=document.forms["myForm1"];
oForm.camera[iNum].checked=true;
}
</script>
</head>
<body>
<form method="post" name="myForm1" action="">
<p>您使用的相机品牌</p>
<p>
<input type="radio" name="camera" id="canon" value="Canon">
<label for="canon">Canon</label>
</p>
<p>
<input type="radio" name="camera" id="nikon" value="Nikon">
<label for="nikon">Nikon</label>
</p>
<p>
<input type="radio" name="camera" id="sony" value="Sony">
<label for="sony">Sony</label>
</p>
<p>
<input type="radio" name="camera" id="pentax" value="Tentax">
<label for="pentax">Tentax</label>
</p>
<p>
<input type="button" value="检查选中对象" onClick="getChoice();">
<input type="button" value="设置为Canon" onClick="setChoice(0);">
</p>
</form>
</body>
</html>

复选框的全选、全不选与反选

3.配置复选框

代码：

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<title>js操作表单</title>
<script language="javascript">
function changeBoxes(action){
var oForm=document.forms["myForm1"];
var oCheckBox=oForm.hobby;
for(var i=0;i<oCheckBox.length;i++)//遍历每一个选项
if(action<0) //反选
oCheckBox[i].checked=!oCheckBox[i].checked;
else
oCheckBox[i].checked=action;
}
</script>
</head>
<body>
<form method="post" name="myForm1" action="">
<p>
<input type="checkbox" name="hobby" id="ball" value="ball">
<label for="ball">打球</label>
</p>
<p>
<input type="checkbox" name="hobby" id="TV" value="TV">
<label for="TV">看电视</label>
</p>
<p>
<input type="checkbox" name="hobby" id="net" value="net">
<label for="net">上网</label>
</p>
<p>
<input type="checkbox" name="hobby" id="book" value="book">
<label for="book">看书</label>
</p>
<p>
<input type="checkbox" name="hobby" id="run" value="run">
<label for="run">跑步</label>
</p>
<p>
<input type="button" value="全选" onClick="changeBoxes(1);">
<input type="button" value="全不选" onClick="changeBoxes(0);"/>
<input type="button" value="反选" onClick="changeBoxes(-1);"/>
</p>
</form>
</body>
</html>

下拉菜单选中项读取

4.配置下拉菜单

下拉菜单中最关键的是访问用户选中的选项，对于单选下拉菜单可通过selectedIndex属性轻松访问选项。

代码：

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<title>js操作表单</title>
<script language="javascript">
function checkSingle(){
var oForm=document.forms["myForm1"];
var oSelectBox=oForm.constellation;
var iChoice=oSelectBox.selectedIndex;//获取选中项
alert("您选中了："+oSelectBox.options[iChoice].text);
}
</script>
</head>
<body>
<form method="post" name="myForm1" action="">
<p>
</p>
<p>
<input type="button" value="查看选项" onClick="checkSingle();" />
</p>
</form>
</body>
</html>