JSFiddle - React, Tailwind, and code Playground

HTML

<form role="form" id="form" class="form-horizontal">
    <div class="form-group">
        <div class="row">
            <div class="col-md-3 portfolio-item">
                 <h5>Region</h5>

                <select class="form-control" name="region" id="region">
                    <option value="">Select a Region</option>
                    <option value="US">US</option>
                    <option value="UK">UK</option>
                    <option value="XS">XS (Sales Team)</option>
                    <option value="XT">XT (Editorial Test)</option>
                </select>
            </div>
            <div class="col-md-3 portfolio-item">
                 <h5>Duration</h5>

                <select class="form-control" name="duration" id="duration">
                    <option value="">Select a Duration</option>
                    <option value="5">5 Minutes</option>
                    <option value="10">10 Minutes</option>
                    <option value="15">15 Minutes</option>
                    <option value="20">20 Minutes</option>
                    <option value="25">25 Minutes</option>
                    <option value="30">30 Minutes</option>
                </select>
            </div>
            <div class="col-md-3 portfolio-item">
                <input type="submit" class="btn btn-default" id="submit" />
            </div>
        </div>
    </div>
</form> 
<a id="link" href>JSON feed</a>

JavaScript

document.getElementById('submit').onclick = updateLink;

function updateLink(e) {
    e.preventDefault();

    var regionBox = document.getElementById('region'),
        region = regionBox.options[regionBox.selectedIndex].value,
        durationBox = document.getElementById('duration'),
        duration = durationBox.options[durationBox.selectedIndex].value,
        link = document.getElementById('link'),
        newHref = '/editoralPortal/?region=' + region + '&duration=' + duration;

    link.href = newHref;

    // prevent form submission
    return false;
}