jquery button value

HTML

<button value="black" class="black btn">Black</button>
<button value="red" class="red btn">Red</button>
<button value="brown" class="brown btn">Brown</button>
<button value="orange" class="orange btn">Orange</button>
<button value="mediumSeaGreen" class="green btn">MediumSeaGreen</button>

CSS

body {
    -webkit-transition: .6s ease;
    -moz-transition: .6s ease;
    -ms-transition: .6s ease;
    -o-transition: .6s ease;
}

btn {
    width: 200px;
    background: red;
    display: inline-block;
}

JavaScript

$('.btn').on('click', function() {
    var valColor = $(this).val();

    $('btn').css({
        background: valColor        
    });
});