How to loop through checkboxes or radio button groups via JavaScript

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Do you have a form with checkboxes or radio buttons that you would like to loop through via JavaScript? This JavaScript function will do just that!

Demo
I like to program in:

PHP

Perl

Ruby

ASP

I like to eat:

Snickers

Hershey's

M&M's

Nerds

I like to drink:

Coke

Gatorade

Pepsi

Milk




Here is the plain HTML:

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<form name="thisForm">
I like to program in:<p>
<input type="checkbox" value="PHP" CHECKED>PHP<p>
<input type="checkbox" value="Perl">Perl<p>
<input type="checkbox" value="Ruby">Ruby<p>
<input type="checkbox" value="ASP">ASP<p>
<hr>
I like to eat:<p>
<input type="radio" value="Snickers" name="candy" CHECKED>Snickers<p>
<input type="radio" value="Hershey's" name="candy">Hershey's<p>
<input type="radio" value="M&M's" name="candy">M&M's<p>
<input type="radio" value="Nerds" name="candy">Nerds<p>
<hr>
I like to drink:<p>
<input type="radio" value="Coke" name="drink" CHECKED>Coke<p>
<input type="radio" value="Gatorade" name="drink">Gatorade<p>
<input type="radio" value="Pepsi" name="drink">Pepsi<p>
<input type="radio" value="Milk" name="drink">Milk<p>
<br>
<input type="button" value="Submit" onclick="loopForm(document.thisForm);"> 
</form>
<p>
<div id="cbResults"></div>
<div id="radioResults"></div>

As usual, there is not too much action going on here. It is just a plain form with some checkboxes and 2 radio button groups called candy and drink. Radio buttons with the same name will be grouped and allows the users to only select one option out of the entire group. The submit button will launch the loopForm JavaScript function and the myForm DOM object is passed over as an argument. There are also 2 divs in lines 23-24 where are checkbox and radio button results will be posted. Now, on to more exciting things.

Here is the JavaScript code:

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function loopForm(form) {
    var cbResults = 'Checkboxes: ';
    var radioResults = 'Radio buttons: ';
    for (var i = 0; i < form.elements.length; i++ ) {
        if (form.elements[i].type == 'checkbox') {
            if (form.elements[i].checked == true) {
                cbResults += form.elements[i].value + ' ';
            }
        }
        if (form.elements[i].type == 'radio') {
            if (form.elements[i].checked == true) {
                radioResults += form.elements[i].value + ' ';
            }
        }
    }
    document.getElementById("cbResults").innerHTML = cbResults;
    document.getElementById("radioResults").innerHTML = radioResults;
}

This function loops through all the elements in the form that was passed over to the function.

If the element is of checkbox type and it is checked, the value of this element will be appended to our cbResults variable which is keeping track of our checkbox results.

If the element is of radio type and it is checked, the value of this element will be appended to our radioResults variable which is keeping track of our radio button results.

After all the looping is finished, the results are cbResults and radioResults are inserted into the cbResults div and radioResults div respectively.

If you found that my code was helpful in any way, shape, or form and would like to buy me a beer, please use the Donate button below =) Cheers!