写在今天

<script type="text/javascript">
<!--
// return the value of the radio button that is checked
// return an empty string if none are checked, or
// there are no radio buttons
function getCheckedValue(radioObj) {
if(!radioObj)
return "";
var radioLength = radioObj.length;
if(radioLength == undefined)
if(radioObj.checked)
return radioObj.value;
else
return "";
for(var i = 0; i < radioLength; i++) {
if(radioObj[i].checked) {
return radioObj[i].value;
}
}
return "";
}

// set the radio button with the given value as being checked
// do nothing if there are no radio buttons
// if the given value does not exist, all the radio buttons
// are reset to unchecked
function setCheckedValue(radioObj, newValue) {
if(!radioObj)
return;
var radioLength = radioObj.length;
if(radioLength == undefined) {
radioObj.checked = (radioObj.value == newValue.toString());
return;
}
for(var i = 0; i < radioLength; i++) {
radioObj[i].checked = false;
if(radioObj[i].value == newValue.toString()) {
radioObj[i].checked = true;
}
}
}
//-->
</script>

<form name="radioExampleForm" method="get" action="" onsubmit="return false;">
<p><label for="number0"><input type="radio" value="0" name="number" id="number0"> Zero</label>
 <label for="number1"><input type="radio" value="1" name="number" id="number1"> One</label>
 <label for="number2"><input type="radio" value="2" name="number" id="number2"> Two</label>
 <label for="number3"><input type="radio" value="3" name="number" id="number3"> Three</label>
 <label for="number4"><input type="radio" value="4" name="number" id="number4"> Four</label>
<p><input type="button" onclick="alert('Checked value is: '+getCheckedValue(document.forms['radioExampleForm'].elements['number']));" value="Show Checked Value">
 <input type="button" onclick="setCheckedValue(document.forms['radioExampleForm'].elements['number'], '2');" value="Set Checked to Two">
 <input type="button" onclick="setCheckedValue(document.forms['radioExampleForm'].elements['number'], '4');" value="Set Checked to Four">
 <input type="button" onclick="setCheckedValue(document.forms['radioExampleForm'].elements['number'], '');" value="Uncheck All">
</form>