W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<style>
canvas {
    border:1px solid #d3d3d3;
    background-color: #f1f1f1;
}
</style>
</head>
<body onload="startGame()">
<script>

var redGamePiece, blueGamePiece, yellowGamePiece;

function startGame() {
    redGamePiece = new component(75, 75, "red", 10, 10);
    yellowGamePiece = new component(75, 75, "yellow", 50, 60);    
    blueGamePiece = new component(75, 75, "blue", 10, 220);
    myGameArea.start();
}

function component(width, height, color, x, y) {
    this.width = width;
    this.height = height;
    this.x = x;
    this.y = y;    
    this.update = function(){
        ctx = myGameArea.context;
        ctx.fillStyle = color;
        ctx.fillRect(this.x, this.y, this.width, this.height);
    }
}

function updateGameArea() {
    myGameArea.clear();
    redGamePiece.x += 1;
    yellowGamePiece.x += 1;    
    yellowGamePiece.y += 1;        
    blueGamePiece.x += 1;        
    blueGamePiece.y -= 1;            
    redGamePiece.update();
    yellowGamePiece.update();        
    blueGamePiece.update();
}
</script>
<p>The three components moves by changing the x- and y-coordinates on every update.</p>
</body>

</html>

​x
 
<!DOCTYPE html><html><head><meta name="viewport" content="width=device-width, initial-scale=1.0"/><style>canvas {    border:1px solid #d3d3d3;    background-color: #f1f1f1;}</style></head><body onload="startGame()"><script>​var redGamePiece, blueGamePiece, yellowGamePiece;​function startGame() {    redGamePiece = new component(75, 75, "red", 10, 10);    yellowGamePiece = new component(75, 75, "yellow", 50, 60);        blueGamePiece = new component(75, 75, "blue", 10, 220);    myGameArea.start();}​var myGameArea = {    canvas : document.createElement("canvas"),    start : function() {        this.canvas.width = 480;        this.canvas.height = 270;        this.context = this.canvas.getContext("2d");        document.body.insertBefore(this.canvas, document.body.childNodes[0]);        this.interval = setInterval(updateGameArea, 20);    },    clear : function() {        this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);    }}​function component(width, height, color, x, y) {    this.width = width;    this.height = height;    this.x = x;    this.y = y;        this.update = function(){        ctx = myGameArea.context;        ctx.fillStyle = color;