How to get the selected radio button’s value?

Question

I’m having some strange problem with my JS program. I had this working properly but for some reason it’s no longer working. I just want to find the value of the radio button (which one is selected) and return it to a variable. For some reason it keeps returning undefined.

Here is my code:

function findSelection(field) {
    var test = 'document.theForm.' + field;
    var sizes = test;

    alert(sizes);
        for (i=0; i < sizes.length; i++) {
            if (sizes[i].checked==true) {
            alert(sizes[i].value + ' you got a value');     
            return sizes[i].value;
        }
    }
}

submitForm:

function submitForm() {

    var genderS =  findSelection("genderS");
    alert(genderS);
}

HTML:

<form action="#n" name="theForm">

    <label for="gender">Gender: </label>
    <input type="radio" name="genderS" value="1" checked> Male
    <input type="radio" name="genderS" value="0" > Female<br><br>
    <a href="javascript: submitForm()">Search</A>
</form>

Answer 1

ECMAScript 6 version

let genderS = Array.from(document.getElementsByName("genderS")).find(r => r.checked).value;

Answer 2

If it is possible for you to assign a Id for your form element(), this way can be considered as a safe alternative way (specially when radio group element name is not unique in document):

function findSelection(field) {
    var formInputElements = document.getElementById("yourFormId").getElementsByTagName("input");
    alert(formInputElements);
        for (i=0; i < formInputElements.length; i++) {
        if ((formInputElements[i].type == "radio") && (formInputElements[i].name == field) && (formInputElements[i].checked)) {
            alert(formInputElements[i].value + ' you got a value');     
            return formInputElements[i].value;
        }
    }
}

HTML:

<form action="#n" name="theForm" id="yourFormId">

Answer 3

Try this

function findSelection(field) {
    var test = document.getElementsByName(field);
    var sizes = test.length;
    alert(sizes);
    for (i=0; i < sizes; i++) {
            if (test[i].checked==true) {
            alert(test[i].value + ' you got a value');     
            return test[i].value;
        }
    }
}


function submitForm() {

    var genderS =  findSelection("genderS");
    alert(genderS);
    return false;
}

A fiddle here.

Answer 4

Edit: As said by Chips_100 you should use :

var sizes = document.theForm[field];

directly without using the test variable.

---

Old answer:

Shouldn't you eval like this ?

var sizes = eval(test);

I don't know how that works, but to me you're only copying a string.

Answer 5

    var value = $('input:radio[name="radiogroupname"]:checked').val();