Edit in JSFiddle

document.querySelectorAll('.button')[0].addEventListener('click', function(event) {
   console.log('Button clicked'); 
});
<a href="#" class="button">Play</a>
.button {
    width: 100px;
    height: 50px;
    line-height: 50px;
    position: absolute;
    left: 50px;
    top: 50px;
    color: #FFF;
    text-decoration: none;
    background: linear-gradient(#1879BD 50%, #084D79 50%);
    text-align: center;
    font-size: 15px;
    font-family: sans-serif;
}
.button:hover {
    background: linear-gradient(#678834 50%, #093905 50%);
}
.button:active {
    background: linear-gradient(#EB7723 50%, #A80000 50%);
}