canvas.js

var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");

var x = 0;
var y = 0;

function drawShape() {
  ctx.fillRect(x, y, 150, 80);
}

function clearCanvas() {
  ctx.clearRect(0,0,canvas.width, canvas.height)
}

function moveRight() {
  x = x + 10;
  clearCanvas();
  drawShape();
}

function moveLeft() {

}

function moveUp() {

}

function moveLeft() {

}

function keyClicked(event) {
  console.log("a key was clicked " + event.keyCode);
  if (event.keyCode == 39) {
    moveRight();
  }

}

// register an event handler for detecting keyboard events
document.addEventListener("keydown", keyClicked)
drawShape()