Edit in JSFiddle

var myGamePiece;

function startGame() {
  myGamePiece = new component(30, 30, "red", 80, 75);
  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);
  },
  stop: function() {
    clearInterval(this.interval);
  },
  clear: function() {
    this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
  }
}

function component(width, height, color, x, y, type) {
  this.type = type;
  this.width = width;
  this.height = height;
  this.x = x;
  this.y = y;
  this.speedX = 0;
  this.speedY = 0;
  this.gravity = 0.1;
  this.gravitySpeed = 0;
  this.bounce = 0.6;
  this.update = function() {
    ctx = myGameArea.context;
    ctx.fillStyle = color;
    ctx.fillRect(this.x, this.y, this.width, this.height);
  }
  this.newPos = function() {
    this.gravitySpeed += this.gravity;
    this.x += this.speedX;
    this.y += this.speedY + this.gravitySpeed;
    this.hitBottom();
  }
  this.hitBottom = function() {
    var rockbottom = myGameArea.canvas.height - this.height;
    if (this.y > rockbottom) {
      this.y = rockbottom;
      this.gravitySpeed = -(this.gravitySpeed * this.bounce);
    }
  }
}

function updateGameArea() {
  myGameArea.clear();
  myGamePiece.newPos();
  myGamePiece.update();
}


startGame();

<p>The bouncing property indicates how strong a component will bounce back, after hitting the ground.</p>
<p>Set the bouncing property to a decimal number between 0 and 1.</p>
<p>0 = no bouncing.</p>
<p>1 = will bounce all the way back.</p>

canvas {
  border: 1px solid #d3d3d3;
  background-color: #f1f1f1;
}