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


Question

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?

2020/08/03
1
280
8/3/2020 9:38:17 PM


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.

2009/09/14

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;       
    }
}
2009/09/14

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

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.

2017/05/23

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");
}
2014/06/11

You can use this simple script. You may have multiple radio buttons with same names and different values.

var checked_gender = document.querySelector('input[name = "gender"]:checked');

if(checked_gender != null){  //Test if something was checked
alert(checked_gender.value); //Alert the value of the checked.
} else {
alert('Nothing checked'); //Alert, nothing was checked.
}
2017/11/05

Source: https://stackoverflow.com/questions/1423777
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