javascript selected radio

I want to check what is the selected radio input.

here is my code.

<input name="u_type" type="radio" value="staff" id="u_type" checked="checked" /> Staff
<input name="u_type" type="radio" value="admin" id="u_type" /> Admin
<input id="add_user" name="add_user" type="button" onclick="addUser();"  value="Add" class="submi开发者_JAVA技巧tButton admin_add" />

function addUser()
{
//how to check what is the selected radio input
}

thanks.

function addUser() {
    //how to check what is the selected radio input
    alert(getCheckedRadioValue('u_type'));
}

function getCheckedRadioValue(name) {
    var elements = document.getElementsByName(name);

    for (var i=0, len=elements.length; i<len; ++i)
        if (elements[i].checked) return elements[i].value;
}

And element's IDs must be different.

To get the value of the checked radio button, without jQuery:

var radios = document.getElementsByName("u_type");
for(var i = 0; i < radios.length; i++) {
    if(radios[i].checked) selectedValue = radios[i].value;   
}

(assuming that selectedValue is a variable declared elsewhere)

$('input[name=u_type]:checked').val()

will get you the value of the selected option which you can, of course, assign to a variable. Due to admonishment, I should also point out that this is jquery, a handy javascript library for making DOM manipulation easier and with excellent cross-browser compatibility. It can be found here.

Alternatively to kmb385's suggestion you could wrap your inputs in a form, and make sure all of the input names are different (you have two u_type) names.

Then you can access the inputs as document.formname.inputname.checked, which will return true or false.

I know this is an old question, but the answers given seem overly complex.

As pointed out earlier, you should not have two elements with the same id. That violates the html spec. Just remove the id attributes, or make them two different values. Then simply use this to get the checked value:

document.querySelector("input[type='radio'][name='u_type']:checked").value

You shouldn't have two radio elements with the same id. You need to change one of the ids then check both radio buttons like:

if(document.getElementById("u_type").checked == true)
{
   //do something
}

I would recommend using jquery to do this instead of native js.

The following is the jQuery implementation to get the value of a radio button

$("#u_type").click(function() {
var value = $(this).val();
});

If you want to use javascript, then:

function get_radio_value()
{
for (var i=0; i < document.form.u_type.length; i++)
{
   if (document.form.u_type[i].checked)
   {
   var val = document.form.u_type[i].value;
   }
  }
}