Simple game for my tumblr

tumblr_game.js

var CANVAS_WIDTH = 200,
    CANVAS_HEIGHT = 100,
    canvas = document.getElementById("microgame"),
    ctx = canvas.getContext("2d"),
    player = {
        x: 30,
        y: CANVAS_HEIGHT - 20,
        w: 20,
        h: 20,
        score: 0,
        jumping: false,
        jumpingTimer: 0,
        falling: false,
        gliding: false
    },
    enemies = [],
    spawnEnemyTimer = 0,
    nextEnemySpawn = 1,
    lastUpdate = +new Date;
    
canvas.width = CANVAS_WIDTH;
canvas.height = CANVAS_HEIGHT;

function quadsCollision(quad_1, quad_2) {
    var x1_1, y1_1, x1_2, y1_2,
        x2_1, y2_1, x2_2, y2_2;

    x1_1 = quad_1.x;
    y1_1 = quad_1.y;
    x2_1 = quad_1.x + quad_1.w;
    y2_1 = quad_1.y + quad_1.h;
    x1_2 = quad_2.x;
    y1_2 = quad_2.y;
    x2_2 = quad_2.x + quad_2.w;
    y2_2 = quad_2.y + quad_2.h;

    return (x1_1 < x2_2) && (x2_1 > x1_2) && (y1_1 < y2_2) && (y2_1 > y1_2);
}

function update(dt) {
    var i, l, toRemove = [];

    if (player.jumping) {
        player.y -= 150 * dt;
        player.jumpingTimer += dt;
        if (player.jumpingTimer > 0.35) {
            player.falling = true;
            player.jumping = false;
        }
    } else {
        var vy = player.gliding ? 25 : 100;
        
        player.y = player.y >= canvas.height - 20 ? canvas.height - 20 : player.y + vy * dt;
        if (player.falling && player.y === canvas.height - 20) {
            player.falling = false;
            player.gliding = false;
        }
    }
    
    for (i = 0, l = enemies.length; i < l; i += 1) {
        enemies[i].x += enemies[i].vx * dt;
        
        if (quadsCollision(player, enemies[i])) {
            reset();
            return;
        }
        
        if (enemies[i].x < -20) {
            player.score += 1;
            toRemove.push(i);
        }
    }
    
    for (i = 0, l = toRemove.length; i < l; i += 1) {
        enemies.splice(toRemove[i], 1);
    }
    
    spawnEnemyTimer += dt;
    if (spawnEnemyTimer > nextEnemySpawn) {
        var enemy = {
            x: canvas.width,
            vx: -90 - 10 * Math.random(),
            y: canvas.height - 20,
            w: 20,
            h: 20,
            inverted: false
        };
        if (Math.round(Math.random() % 2) === 0) {
            enemy.y = canvas.height - 50;
            enemy.inverted = true;
        }
        enemies.push(enemy);
        spawnEnemyTimer = 0;

        nextEnemySpawn = 0.5 + Math.random() * 1 ;
    }
}

function draw() {
    var i, l;
    
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.fillStyle = "black";
    ctx.fillRect(player.x, player.y, player.w, player.h);
    ctx.fillStyle = "white";
    
    for (i = 0, l = enemies.length; i < l; i += 1) {
        ctx.save();
        ctx.translate(enemies[i].x, enemies[i].y);
        ctx.beginPath();
        if (enemies[i].inverted) {
            ctx.moveTo(0, 0);
            ctx.lineTo(20, 0);
            ctx.lineTo(10, 20);
        } else {
            ctx.moveTo(0, 20);
            ctx.lineTo(20, 20);
            ctx.lineTo(10, 0);
        }
        ctx.stroke();
        ctx.fill();
        ctx.restore();
        //ctx.strokeRect(enemies[i].x, enemies[i].y, 20, 20);
    }

    ctx.font = "15px Courier";
    ctx.fillText("Score: " + player.score, 0, 10);
}

function loop() {
    var now = +new Date,
        dt = (now - lastUpdate) / 1000;
    
    update(dt);
    draw();
    lastUpdate = now;
    
    window.requestAnimationFrame(loop);
}

function reset() {
    enemies = [];
    player.score = 0;
    player.y = CANVAS_HEIGHT - 20;
    player.jumping = false;
    spawnEnemyTimer = 0;
}

window.addEventListener("keydown", function (event) {
  if (event.keyCode == 32) {
      if (player.falling) {
          player.gliding = true;
      } else if (!player.jumping) {
          player.jumping = true;
          player.jumpingTimer = 0;
      }
  }
  event.preventDefault();
});

window.addEventListener("keyup", function (event) {
    if (event.keyCode == 32) {
      if (player.falling) {
          player.gliding = false;
      }
    }
});

canvas.addEventListener("mousedown", function (event) {
  console.log(event);
});


loop();