Image Cover

image_cover.js

/*
See JSFiddle for combined HTML/CSS/JS
http://jsfiddle.net/66c43ao1/
*/
$('.cover').each(function() {
    var containerHeight = $(this).height(),
        containerWidth  = $(this).width(),
        image           = $(this).children('img'),
        imageHeight     = image.attr('height'),
        imageWidth      = image.attr('width'),
        newHeight       = imageHeight,
        newWidth        = imageWidth;

    if (imageWidth < containerWidth) {
        // if the image isn't wide enough to cover the space, scale the width
        newWidth        = containerWidth;
        newHeight       = imageHeight * newWidth/imageWidth;
    }
    if (imageHeight < containerHeight) {
        // if the image isn't tall enough to cover the space, scale the height
        newHeight       = containerHeight;
        newWidth        = imageWidth * newHeight/imageHeight;
    }

    var marginLeft      = (newWidth - containerWidth)/2;
    var marginTop       = (newHeight - containerHeight)/2;

    image.css({
        marginLeft  : '-' + marginLeft + 'px',
        marginTop   : '-' + marginTop + 'px',
        height      : newHeight,
        width       : newWidth
    });
});

Sample HTML

<div class="test">
    <div class="cover">
        <img src="http://d2ws0xxnnorfdo.cloudfront.net/character/meme/cool-dog.jpg" width="590" height="590"/>
    </div>
</div>

Sample CSS

/* modify the width and height below to demonstrate coverage */
.test {
    height: 300px;
    position: relative;
    width: 500px;
}
/* you will need the below styles */
.cover {
    height: 100%;
    left: 0;
    overflow: hidden;
    position: absolute;
    top: 0;
    width: 100%;
    z-index: 1;
}