How can I check whether a radio button is selected with JavaScript?

How can I check whether a radio button is selected with JavaScript?

I have two radio buttons within an HTML form. A dialog box appears when one of the fields is null. How can I check whether a radio button is selected?

Solutions/Answers:

Solution 1:

Let’s pretend you have HTML like this

<input type="radio" name="gender" id="gender_Male" value="Male" />
<input type="radio" name="gender" id="gender_Female" value="Female" />

For client-side validation, here’s some Javascript to check which one is selected:

if(document.getElementById('gender_Male').checked) {
  //Male radio button is checked
}else if(document.getElementById('gender_Female').checked) {
  //Female radio button is checked
}

The above could be made more efficient depending on the exact nature of your markup but that should be enough to get you started.


If you’re just looking to see if any radio button is selected anywhere on the page, PrototypeJS makes it very easy.

Here’s a function that will return true if at least one radio button is selected somewhere on the page. Again, this might need to be tweaked depending on your specific HTML.

function atLeastOneRadio() {
    return ($('input[type=radio]:checked').size() > 0);
}

For server-side validation (remember, you can’t depend entirely on Javascript for validation!), it would depend on your language of choice, but you’d but checking the gender value of the request string.

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Solution 2:

With jQuery, it’d be something like

if ($('input[name=gender]:checked').length > 0) {
    // do something here
}

Let me break that down into pieces to cover it more clearly.
jQuery processes things from left to right.

input[name=gender]:checked
  1. input limits it to input tags.
  2. [name=gender] limits it to tags with the name gender within the previous group.
  3. :checked limits it to checkboxes/radio buttons that are selected within the previous group.

If you want to avoid this altogether, mark one of the radio buttons as checked (checked="checked") in the HTML code, which would guarantee that one radio button is always selected.

Solution 3:

A vanilla JavaScript way

var radios = document.getElementsByTagName('input');
var value;
for (var i = 0; i < radios.length; i++) {
    if (radios[i].type === 'radio' && radios[i].checked) {
        // get value, set checked flag or do whatever you need to
        value = radios[i].value;       
    }
}

Solution 4:

Just trying to improve on Russ Cam’s solution with some CSS selector sugar thrown in with the vanilla JavaScript.

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var radios = document.querySelectorAll('input[type="radio"]:checked');
var value = radios.length>0? radios[0].value: null;

No real need for jQuery here, querySelectorAll is widely supported enough now.

Edit: fixed a bug with the css selector, I’ve included the quotes, although you can omit them, in some cases you can’t so it’s better to leave them in.

Solution 5:

HTML Code

<input type="radio" name="offline_payment_method" value="Cheque" >
<input type="radio" name="offline_payment_method" value="Wire Transfer" >

Javascript Code:

var off_payment_method = document.getElementsByName('offline_payment_method');
var ischecked_method = false;
for ( var i = 0; i < off_payment_method.length; i++) {
    if(off_payment_method[i].checked) {
        ischecked_method = true;
        break;
    }
}
if(!ischecked_method)   { //payment method button is not checked
    alert("Please choose Offline Payment Method");
}

Solution 6:

The scripts in this page helped me come up with the script below, which I think is more complete and universal. Basically it will validate any number of radio buttons in a form, meaning that it will make sure that a radio option has been selected for each one of the different radio groups within the form. e.g in the test form below:

   <form id="FormID">

    Yes <input type="radio" name="test1" value="Yes">
    No <input type="radio" name="test1" value="No">

    <br><br>

    Yes <input type="radio" name="test2" value="Yes">
    No <input type="radio" name="test2" value="No">

   <input type="submit" onclick="return RadioValidator();">

The RadioValidator script will make sure that an answer has been given for both ‘test1’ and ‘test2’ before it submits. You can have as many radio groups in the form, and it will ignore any other form elements. All missing radio answers will show inside a single alert popup. Here it goes, I hope it helps people. Any bug fixings or helpful modifications welcome 🙂

<SCRIPT LANGUAGE="JAVASCRIPT">
function RadioValidator()
{
    var ShowAlert = '';
    var AllFormElements = window.document.getElementById("FormID").elements;
    for (i = 0; i < AllFormElements.length; i++) 
    {
        if (AllFormElements[i].type == 'radio') 
        {
            var ThisRadio = AllFormElements[i].name;
            var ThisChecked = 'No';
            var AllRadioOptions = document.getElementsByName(ThisRadio);
            for (x = 0; x < AllRadioOptions.length; x++)
            {
                 if (AllRadioOptions[x].checked && ThisChecked == 'No')
                 {
                     ThisChecked = 'Yes';
                     break;
                 } 
            }   
            var AlreadySearched = ShowAlert.indexOf(ThisRadio);
            if (ThisChecked == 'No' && AlreadySearched == -1)
            {
            ShowAlert = ShowAlert + ThisRadio + ' radio button must be answered\n';
            }     
        }
    }
    if (ShowAlert != '')
    {
    alert(ShowAlert);
    return false;
    }
    else
    {
    return true;
    }
}
</SCRIPT>