JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <img src='http://upload.wikimedia.org/wikipedia/commons/8/84/Example.svg' />
</div>

CSS

div {
    width: 200px;
    height: 300px;
    border: 1px solid cyan;
}
img {
    width: 100%;
}

JavaScript

$(function() {
        var myImage = $('img'),
            originalHeight = myImage.height();
        
        getImgSize(myImage, originalHeight, myImage[0].src);
    });
    
    /* http://stackoverflow.com/questions/1944280/determine-original-size-of-image-cross-browser */
    function getImgSize(myImage, currentHeight, imgSrc) {
        var newImg = new Image();
    
        newImg.onload = function() {
            if(newImg.height > currentHeight) {
               myImage.addClass('smaller');
                alert(newImg.height + ' > ' + currentHeight);
            }
        }
    
        newImg.src = imgSrc;
    }