JSFiddle - React, Tailwind, and code Playground

HTML

<div class="support-test">
    iframe Returns
    <output id="iframe-test-supported">testing...</output>
</div>

<div class="support-test">
    jQuery Returns
    <output id="jquery-supported">testing...</output>
</div>

CSS

/* This will break box model detection in IE8 */
* {
    box-sizing: border-box;
}

/* window dressing */
.support-test {
    margin: 5px auto;
    padding: 5px;
    width: 100px;
    text-align: center;
    font-family: Arial;
    font-size: 10px;
    font-weight: bold;
    text-transform: uppercase;
    background-color: #efefef;
    color: #111;
}

.support-test output {
    display: block;
    color: white;
    margin: 5px 0 0;
    padding: 5px;
}

.true {
    background-color: green;
}

.false {
    background-color: red;
}

JavaScript

function do_test () {
    var support_boxModel = false,
        iframe = document.createElement("iframe"),
        i_window,
        i_document,
        div,
        html;
    
    iframe.id = "test-iframe";
    document.body.appendChild(iframe);

    i_window = frames[iframe.id];
    i_document = i_window.document;
    
    div = i_document.createElement("div");
    
    div.style.width = div.style.padding = "1px";
    div.style.border = 0;
    div.style.overflow = "hidden";
    div.style.display = "block";
    
    // for some reason IE doesn't automatically add a body
    // or html element to a brand new iframe
    if (!i_document.documentElement) {
         html = i_document.createElement("html");
         i_document.appendChild(html);
         html.appendChild(i_document.createElement("body"));
    }

    i_document.body.appendChild(div);
    
    support_boxModel = div.offsetWidth === 3;
    
    document.body.removeChild(iframe);
    
    return support_boxModel;
}

// IE doesn't recognize HTML5
document.createElement("output");

$(function () {
    var boxModel = do_test();
    
    $("#iframe-test-supported").text(boxModel).addClass(boxModel.toString());
    $("#jquery-supported").text($.support.boxModel).addClass($.support.boxModel.toString());
});