Talking to the DOM Elements

var update = function(args, ctx){
    // Get the span element from the HTML Entity
    var selection = document.getElementById('selected');

    // Create a click handler function
    ctx.handleClick = function(event){
        var x = event.offsetX;
        var y = event.offsetY;
        ctx.world.gooRunner.pick(x, y, function(index, depth){
            if(index !== -1){
                var entity = ctx.world.entityManager.getEntityByIndex(index);
                selection.innerHTML = entity.name;
            } else {
                selection.innerHTML = 'Nothing';
            }
        });
    };

    // Attach the click handler
    ctx.domElement.addEventListener('click', ctx.handleClick);

if (selection.innerHTML === "Nothing"){
console.log("Nothing Selected");
} else if (selection.innerHTML === "12A02") {
console.log("12A02 Selected");
} else if(selection.innerHTML === "12B13") {
console.log("12B13 Selected");
}
}

var cleanup = function(args, ctx){
    // Remove the click handler
    ctx.domElement.removeEventListener('click', ctx.handleClick);
}

<style>

#hud {
margin: 25px;
background-color: transparent;
font-weight: bold;
font-family: sans-serif;
font-size: 24px;
color: skyblue;
}

</style>

<p id="hud">
    You have selected: <span id='selected'>Nothing</span>
</p>