Question

我是JavaScript新手，想编写一个以前用Java编写过的游戏。我使用p5.js库进行编码，并使用Atom文本编辑器。我正在制作的游戏是Asteroids，并且运行良好。我已经弄清楚了如何添加飞船和激光器。然后，我添加了实际小行星的代码。（我不确定这是否相关，但是正如我之前说过的，我是从Java项目中复制代码，当我添加小行星时，我基本上复制了整个内容，直到保存完为止。添加完之后，我尝试运行它，并说“未定义小行星”，因为我忘记了在HTML中添加对它的引用。但是，在我再次运行它之后，该页面停止加载并最终崩溃（显示“ Aw，Snap！显示此网页时出了点问题”错误）。我最初以为是HTML，但是当我将类添加到主脚本时，它仍然崩溃。一个小时后，我意识到，如果在类名（class ship（）{}）上加上括号，则会加载该页面。但是，我会得到预期的语法错误。如果像在Java中那样将对象声明为类（Ship ship；），将会发生相同的事情，它将运行，但是会显示“ Uncaught SyntaxError：Unexpected identifier”。我不确定如何解决这个问题，或者为什么不将括号添加到类名会导致程序无法运行。

附件是我的主要脚本的第一部分，我的飞船类的构造函数和我的小行星类，因为问题只有在添加它之后才开始。

任何帮助或解决此问题的方法将不胜感激。

主脚本：

let ship;
let bullets = [];
let asteroids = [];
//             Left   Right  Boost  Slow   Shoot
let keyDown = [false, false, false, false, false];
function setup(){
  window.canvas = createCanvas(800, 600);
  ship = new Ship(width/2, height/2);
  for(let i = 0; i = 4; i++){
    asteroids.push(new asteroid(random(width), random(height), 100));
  }
  frameRate(60);

}

function draw(){
  background(0);
  checkKeys();
  ship.update();
  ship.show();

  for(let i = bullets.length-1; i >= 0; i--){
    bullets[i].update();
    bullets[i].show();

    if(!bullets[i].alive){
      bullets.splice(i, 1);
    }
  }

  for(let i = asteroids.length-1; i >= 0; i--){
    asteroids[i].update();
    asteroids[i].show();
  }

}

船级：

class Ship{
  constructor(x, y){
    this.x = x;
    this.y = y;
    this.velX = 0;
    this.velY = 0;
    this.midX = this.x + 15;
    this.midY = this.y + 20;
    this.heading = 0;
    this.rotation = 0;
    this.boosting = false;
  }

小行星类：

class asteroid{
  constructor(x, y, size){
    this.x = x;
    this.y = y;
    this.size = size;
    this.velX = random(-2, 3);
    this.velY = random(-2, 3);

    if(this.velX == 0){
      this.velX++;
    }

    if(this.velY == 0){
      this.velY++;
    }

    this.points = random(4, 12);
    this.xPoints = [];
    this.yPoints = [];
    this.offsets = [];

    for(let i = 0; i < this.points; i++){
      this.offsets[i] = random(-size/5, (size/5)+1);
    }
  }

  update(){
    this.x += this.velX;
    this.y += this.velY;
  }

  show(){
    stroke(255);

    beginShape();
    for(let i; i < this.points; i++){
      let angle = i*(360/this.points);
      let px = (this.size/2 + this.offsets[i]) * cos(angle);
      let py = (this.size/2 + this.offsets[i]) * sin(angle);
      this.xPoints[i] = px + this.x;
      this.yPoints[i] = py + this.y;
      vertex(px, py);
    }
    endShape(CLOSE);
  }
}

Answer 1

运行代码，我遇到了同样的错误。原来您的ship类没有该类的闭括号}，仅对于构造函数而言。添加，现在我没有错误

let ship;
let bullets = [];
let asteroids = [];
//             Left   Right  Boost  Slow   Shoot
let keyDown = [false, false, false, false, false];
function setup(){
  window.canvas = createCanvas(800, 600);
  ship = new Ship(width/2, height/2);
  for(let i = 0; i = 4; i++){
    asteroids.push(new asteroid(random(width), random(height), 100));
  }
  frameRate(60);

}

function draw(){
  background(0);
  checkKeys();
  ship.update();
  ship.show();

  for(let i = bullets.length-1; i >= 0; i--){
    bullets[i].update();
    bullets[i].show();

    if(!bullets[i].alive){
      bullets.splice(i, 1);
    }
  }

  for(let i = asteroids.length-1; i >= 0; i--){
    asteroids[i].update();
    asteroids[i].show();
  }

}


class Ship{
  constructor(x, y){
    this.x = x;
    this.y = y;
    this.velX = 0;
    this.velY = 0;
    this.midX = this.x + 15;
    this.midY = this.y + 20;
    this.heading = 0;
    this.rotation = 0;
    this.boosting = false;
  }
}  //<--- I added this bracket


class asteroid{
  constructor(x, y, size){
    this.x = x;
    this.y = y;
    this.size = size;
    this.velX = random(-2, 3);
    this.velY = random(-2, 3);

    if(this.velX == 0){
      this.velX++;
    }

    if(this.velY == 0){
      this.velY++;
    }

    this.points = random(4, 12);
    this.xPoints = [];
    this.yPoints = [];
    this.offsets = [];

    for(let i = 0; i < this.points; i++){
      this.offsets[i] = random(-size/5, (size/5)+1);
    }
  }

  update(){
    this.x += this.velX;
    this.y += this.velY;
  }

  show(){
    stroke(255);

    beginShape();
    for(let i; i < this.points; i++){
      let angle = i*(360/this.points);
      let px = (this.size/2 + this.offsets[i]) * cos(angle);
      let py = (this.size/2 + this.offsets[i]) * sin(angle);
      this.xPoints[i] = px + this.x;
      this.yPoints[i] = py + this.y;
      vertex(px, py);
    }
    endShape(CLOSE);
  }
}

仅当类文件名称中包含括号

1 个答案: