--description--

When working with objects where the property name and value are the same, you can use the shorthand property name syntax. This syntax allows you to omit the property value if it is the same as the property name.

// using shorthand property name syntax
obj = {
  a, b, c
}

The following code is the same as:

obj = {
  a: a,
  b: b,
  c: c
}

Inside the constructor, add this.position and assign it an object with the x and y coordinates. Make sure to use the shorthand property syntax .

--hints--

You should have a this.position property.

assert.match(Platform.toString(), /this\.position\s*;?/);

The this.position property should be an object with the x and y coordinates. Make sure to use the shorthand property syntax.

assert.match(Platform.toString(), /this\.position\s*=\s*\{\s*x\s*:\s*x\s*,\s*y\s*:\s*y\s*,?\s*\}\s*;?/);
assert.match(code, /this\.position\s*=\s*\{\s*x\s*,\s*y\s*,?\s*\}/);

--seed--

--seed-contents--

html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Learn Intermediate OOP by Building a Platformer Game</title>
    <link rel="stylesheet" href="./styles.css" />
  </head>
  <body>
    <div class="start-screen">
      <h1 class="main-title">freeCodeCamp Code Warrior</h1>
      <p class="instructions">
        Help the main player navigate to the yellow checkpoints.
      </p>
      <p class="instructions">
        Use the keyboard arrows to move the player around.
      </p>
      <p class="instructions">You can also use the spacebar to jump.</p>

      <div class="btn-container">
        <button class="btn" id="start-btn">Start Game</button>
      </div>
    </div>

    <div class="checkpoint-screen">
      <h2>Congrats!</h2>
      <p>You reached the last checkpoint.</p>
    </div>

    <canvas id="canvas"></canvas>

    <script src="./script.js"></script>
  </body>
</html>

css

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --main-bg-color: #0a0a23;
  --section-bg-color: #ffffff;
  --golden-yellow: #feac32;
}

body {
  background-color: var(--main-bg-color);
}

.start-screen {
  background-color: var(--section-bg-color);
  width: 100%;
  position: absolute;
  top: 50%;
  left: 50%;
  margin-right: -50%;
  transform: translate(-50%, -50%);
  border-radius: 30px;
  padding: 20px;
  padding-bottom: 5px;
}

.main-title {
  text-align: center;
}

.instructions {
  text-align: center;
  font-size: 1.2rem;
  margin: 15px;
  line-height: 2rem;
}

.btn {
  cursor: pointer;
  width: 100px;
  margin: 10px;
  color: #0a0a23;
  font-size: 18px;
  background-color: var(--golden-yellow);
  background-image: linear-gradient(#fecc4c, #ffac33);
  border-color: var(--golden-yellow);
  border-width: 3px;
}

.btn:hover {
  background-image: linear-gradient(#ffcc4c, #f89808);
}

.btn-container {
  display: flex;
  align-items: center;
  justify-content: center;
}

.checkpoint-screen {
  position: absolute;
  left: 0;
  right: 0;
  margin-left: auto;
  margin-right: auto;
  width: 100%;
  text-align: center;
  background-color: var(--section-bg-color);
  border-radius: 20px;
  padding: 10px;
  display: none;
}

#canvas {
  display: none;
}

@media (min-width: 768px) {
  .start-screen {
    width: 60%;
    max-width: 700px;
  }

  .checkpoint-screen {
    max-width: 300px;
  }
}

const startBtn = document.getElementById("start-btn");
const canvas = document.getElementById("canvas");
const startScreen = document.querySelector(".start-screen");
const checkpointScreen = document.querySelector(".checkpoint-screen");
const checkpointMessage = document.querySelector(".checkpoint-screen > p");
const ctx = canvas.getContext("2d");
canvas.width = innerWidth;
canvas.height = innerHeight;
const gravity = 0.5;
let isCheckpointCollisionDetectionActive = true;

const proportionalSize = (size) => {
  return innerHeight < 500 ? Math.ceil((size / 500) * innerHeight) : size;
}

class Player {
  constructor() {
    this.position = {
      x: proportionalSize(10),
      y: proportionalSize(400),
    };
    this.velocity = {
      x: 0,
      y: 0,
    };
    this.width = proportionalSize(40);
    this.height = proportionalSize(40);
  }
  draw() {
    ctx.fillStyle = "#99c9ff";
    ctx.fillRect(this.position.x, this.position.y, this.width, this.height);
  }
  
  update() {
    this.draw();
    this.position.x += this.velocity.x;
    this.position.y += this.velocity.y;

    if (this.position.y + this.height + this.velocity.y <= canvas.height) {
      if (this.position.y < 0) {
        this.position.y = 0;
        this.velocity.y = gravity;
      }
      this.velocity.y += gravity;
    } else {
      this.velocity.y = 0;
    }

    if (this.position.x < this.width) {
      this.position.x = this.width;
    }

    if (this.position.x >= canvas.width - this.width * 2) {
      this.position.x = canvas.width - this.width * 2;
    }
  }
}

--fcc-editable-region--

class Platform {
  constructor(x, y) {

  }
}

--fcc-editable-region--

const player = new Player();

const animate = () => {
  requestAnimationFrame(animate);
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  player.update();

  if (keys.rightKey.pressed && player.position.x < proportionalSize(400)) {
    player.velocity.x = 5;
  } else if (keys.leftKey.pressed && player.position.x > proportionalSize(100)) {
    player.velocity.x = -5;
  } else {
    player.velocity.x = 0;
  }
}


const keys = {
  rightKey: {
    pressed: false
  },
  leftKey: {
    pressed: false
  }
};

const movePlayer = (key, xVelocity, isPressed) => {
  if (!isCheckpointCollisionDetectionActive) {
    player.velocity.x = 0;
    player.velocity.y = 0;
    return;
  }

  switch (key) {
    case "ArrowLeft":
      keys.leftKey.pressed = isPressed;
      if (xVelocity === 0) {
        player.velocity.x = xVelocity;
      }
      player.velocity.x -= xVelocity;
      break;
    case "ArrowUp":
    case " ":
    case "Spacebar":
      player.velocity.y -= 8;
      break;
    case "ArrowRight":
      keys.rightKey.pressed = isPressed;
      if (xVelocity === 0) {
        player.velocity.x = xVelocity;
      }
      player.velocity.x += xVelocity;
  }
}

const startGame = () => {
  canvas.style.display = "block";
  startScreen.style.display = "none";
  animate();
}

startBtn.addEventListener("click", startGame);

window.addEventListener("keydown", ({ key }) => {
  movePlayer(key, 8, true);
});

window.addEventListener("keyup", ({ key }) => {
  movePlayer(key, 0, false);
});

Step 66

--description--

--hints--

--seed--

--seed-contents--