百亩森林

This pair of Javascript function can get or set the checked value of a group of radio buttons. These functions are specially designed for dynamic pages, and work without error with zero, one, or more radio buttons. Also, because the radio length is saved before looping, this function is much faster. Finally, the functions are granted to the public domain.
Source Code

// 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;
}
}
}

原帖http://www.somacon.com/p143.php