JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://bootswatch.com/simplex/bootstrap.css">
<link rel="stylesheet" href="http://bootswatch.com/assets/css/bootswatch.min.css">
<script src="http://getbootstrap.com/dist/js/bootstrap.min.js"></script>
<div class="container">
    <div id="content-div" class="row">
        <div class="col-md-3">
            <img class="img-responsive" src="http://placehold.it/100x200" />
        </div>
        <div class="col-md-3">
            <img class="img-responsive" src="http://placehold.it/120x50" />
        </div>
        <div class="col-md-3">
            <img class="img-responsive" src="http://placehold.it/120x50" />
        </div>
        <div class="col-md-3">
            <img class="img-responsive" src="http://placehold.it/120x40" />
        </div>
        <div class="clear"></div>
        <div class="col-md-3">
            <img class="img-responsive" src="http://placehold.it/120x120" />
        </div>
        <div class="col-md-3">
            <img class="img-responsive" src="http://placehold.it/60" />
        </div>
        <div class="col-md-3">
            <img class="img-responsive" src="http://placehold.it/60" />
        </div>
    </div>
    <div class="row">
        <div class="col-md-12">
            <button class="btn">Add more img</button>
            <input type="text" id="width" />
            <input type="text" id="height" />
        </div>
    </div>
</div>

CSS

.img-responsive {
    margin:5px;
}

.clear{
    clear:both;
}

JavaScript

$(function () {
    $('.btn').click(function () {
        var size = $('#width').val().length > 0 ? $('#width').val() : '60' + 'x' + $('#height').val().length > 0 ? $('#height').val() : '60',
            html = '<div class="col-md-3"><img class="img-responsive" src="http://placehold.it/' + size + '" /></div>';
        $('#content-div div:last').after(html);
    });
});