Edit in JSFiddle

var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var ballRadius = 10;
var x = canvas.width / 2;
var y = canvas.height - 30;
var dx = 2;
var dy = -2;
var paddleHeight = 10;
var paddleWidth = 75;
var paddleX = (canvas.width - paddleWidth) / 2;
var rightPressed = false;
var leftPressed = false;
var brickRowCount = 3;
var brickColumnCount = 5;
var brickWidth = 75;
var brickHeight = 20;
var brickPadding = 10;
var brickOffsetTop = 30;
var brickOffsetLeft = 30;

var bricks = [];
for (var c = 0; c < brickColumnCount; c++) {
    bricks[c] = [];
    for (var r = 0; r < brickRowCount; r++) {
        bricks[c][r] = { x: 0, y: 0, status: 1 };
    }
}

document.addEventListener("keydown", keyDownHandler, false);
document.addEventListener("keyup", keyUpHandler, false);

function keyDownHandler(e) {
    if (e.key == "Right" || e.key == "ArrowRight") {
        rightPressed = true;
    }
    else if (e.key == "Left" || e.key == "ArrowLeft") {
        leftPressed = true;
    }
}

function keyUpHandler(e) {
    if (e.key == "Right" || e.key == "ArrowRight") {
        rightPressed = false;
    }
    else if (e.key == "Left" || e.key == "ArrowLeft") {
        leftPressed = false;
    }
}
function collisionDetection() {
    for (var c = 0; c < brickColumnCount; c++) {
        for (var r = 0; r < brickRowCount; r++) {
            var b = bricks[c][r];
            if (b.status == 1) {
                if (x > b.x && x < b.x + brickWidth && y > b.y && y < b.y + brickHeight) {
                    dy = -dy;
                    b.status = 0;
                }
            }
        }
    }
}
function drawBall() {
    ctx.beginPath();
    ctx.arc(x, y, ballRadius, 0, Math.PI * 2);
    ctx.fillStyle = "#0095DD";
    ctx.fill();
    ctx.closePath();
}
function drawPaddle() {
    ctx.beginPath();
    ctx.rect(paddleX, canvas.height - paddleHeight, paddleWidth, paddleHeight);
    ctx.fillStyle = "#0095DD";
    ctx.fill();
    ctx.closePath();
}
function drawBricks() {
    for (var c = 0; c < brickColumnCount; c++) {
        for (var r = 0; r < brickRowCount; r++) {
            if (bricks[c][r].status == 1) {
                var brickX = (c * (brickWidth + brickPadding)) + brickOffsetLeft;
                var brickY = (r * (brickHeight + brickPadding)) + brickOffsetTop;
                bricks[c][r].x = brickX;
                bricks[c][r].y = brickY;
                ctx.beginPath();
                ctx.rect(brickX, brickY, brickWidth, brickHeight);
                ctx.fillStyle = "#0095DD";
                ctx.fill();
                ctx.closePath();
            }
        }
    }
}

function draw() {
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    drawBricks();
    drawBall();
    drawPaddle();
    collisionDetection();

    if (x + dx > canvas.width - ballRadius || x + dx < ballRadius) {
        dx = -dx;
    }
    if (y + dy < ballRadius) {
        dy = -dy;
    }
    else if (y + dy > canvas.height - ballRadius) {
        if (x > paddleX && x < paddleX + paddleWidth) {
            if (y = y - paddleHeight) {
                dy = -dy;
            }
        }
        else {
            alert("GAME OVER");
            document.location.reload();
            clearInterval(interval); // Needed for Chrome to end game
        }
    }

    if (rightPressed && paddleX < canvas.width - paddleWidth) {
        paddleX += 7;
    }
    else if (leftPressed && paddleX > 0) {
        paddleX -= 7;
    }

    x += dx;
    y += dy;
}

var interval = setInterval(draw, 10);
<canvas id="myCanvas" height="320" width="480"></canvas>
canvas { background: #eee; }