js snake game implementation ideas and source code_javascript skills-JS Tutorial-php.cn

js snake game implementation ideas and source code_javascript skills

WBOY

Release： 2016-05-16 15:05:32

Original

3964 people have browsed it

The example in this article shares the relevant code of the js Snake game for your reference. The specific content is as follows

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>贪吃蛇小游戏</title>
  <style>
*{margin:0; padding:0;}
header {
  display: block;
  margin: 0 auto;
  width: 500px;
  text-align: center;
}
header h1 {
  font-family: Arial;
  font-weight: bold;
}
header #newGameButton {
  display: block;
  margin: 20px auto;
  width: 100px;
  padding: 10px 10px;
  background-color: #8f7a66;
  font-family: Arial;
  color: white;
  border-radius: 10px;
  text-decoration: none;
}
header #newGameButton:hover {
  background-color: #9f8b77;
}
header p {
  font-family: Arial;
  font-size: 25px;
  margin: 20px auto;
}
canvas{
  display:block; 
  border:medium double black;
  margin:4px auto;
}
  </style>
</head>
<body>
  <header>
    <h1>贪吃蛇小游戏</h1>
    <a href="javascript:newgame();" id="newGameButton">New Game</a>
    <p>score:<span id="score">0</span></p>
  </header>
  <canvas id="canvas">
    Your browser doesn't support the <code>canvas</code> element.
  </canvas>
  <script>
  var CANVAS = document.getElementById("canvas");
var CTX = CANVAS.getContext("2d");
var SNAKE = new Array();  //用队列模拟蛇身
var DIR = "right";        //用来控制蛇头的方向
var SIZE = 20;        //蛇身的宽度
var FOODX = 0;      //食物的x坐标
var FOODY = 0;      //食物的y坐标
var HEADX = 0;    //蛇头的x坐标
var HEADY = 0;    //蛇头的y坐标
var MAXWIDTH = 200;    //画布的高度
var MAXHEIGHT = 200;  //画布的宽度
var TIME = 400;      //蛇的速度
var SCORE = 0;      //计算玩家分数
var interval = null;

CANVAS.width = MAXWIDTH;
CANVAS.height = MAXHEIGHT;

window.onload = function(){
  newgame();
};
document.getElementById("newGameButton").click(function(){
  newgame();
});
function newgame(){
  SNAKE = [];    //用队列模拟蛇身
  DIR = "right";  //用来控制蛇头的方向
  HEADX = 0;    //蛇头的x坐标
  HEADY = 0;    //蛇头的y坐标
  SCORE = 0;
  window.clearInterval(interval);
  interval = null;
  //初始化画布
  CTX.clearRect(0, 0, MAXWIDTH, MAXHEIGHT);
  //画一条蛇
  drawSnake();
  //放置食物
  setFood();
  //移动蛇
  interval = window.setInterval(move, TIME);

}
function move(){
  switch(DIR){
    case "up":HEADY = HEADY-SIZE;break;
    case "right":HEADX = HEADX+SIZE;break;
    case "down":HEADY = HEADY+SIZE;break;
    case "left":HEADX = HEADX-SIZE;break;
  }
  if(HEADX>MAXWIDTH-SIZE || HEADY>MAXHEIGHT-SIZE || HEADX<0 || HEADY<0){
    alert("你的分数为："+SCORE+"分，继续努力吧!失败原因：碰壁了.....");
    window.location.reload();
  }
  for(var i=1;i<SNAKE.length;i++){
    if(SNAKE[i][0] == SNAKE[0][0] && SNAKE[i][1] == SNAKE[0][1]){
      alert("你的分数为："+SCORE+"分，继续努力吧！失败原因：撞到自己了.....");
      window.location.reload();
    }
  }
  if(SNAKE.length == MAXWIDTH *MAXHEIGHT){
    alert("好厉害!么么哒~");
    window.location.reload();
  }
  moveIn(HEADX, HEADY);//移动一格
}
document.onkeydown = function(e) { //改变蛇方向
  var code = e.keyCode - 37;
  switch(code){
    case 1 : DIR = "up";break;//上
    case 2 : DIR = "right";break;//右
    case 3 : DIR = "down";break;//下
    case 0 : DIR = "left";break;//左
  }
}
//=============================画一条蛇=======================================================
function drawSnake(){
  CTX.fillStyle = "black";
  //画蛇头
  CTX.fillRect (HEADX, HEADY, SIZE, SIZE);
  SNAKE.push([HEADX, HEADY]);
  
  //画蛇身
  switch(DIR){
    case "up": 
      drawBody(HEADX, HEADY + SIZE, HEADX, HEADY + 2 * SIZE);
      break;
    case "right": 
      drawBody(HEADX - SIZE, HEADY, HEADX - 2 * SIZE, HEADY);
      break;
    case "down": 
      drawBody(HEADX, HEADY - SIZE, HEADX, HEADY - 2 * SIZE);
      break;
    case "left": 
      drawBody(HEADX + SIZE, HEADY, HEADX + 2 * SIZE, HEADY);
      break;
  }
}
function drawBody(x1, y1, x2, y2){
  CTX.fillRect (x1, y1, SIZE, SIZE); 
  CTX.fillRect (x2, y2, SIZE, SIZE); 
  SNAKE.push([x1, y1]);
  SNAKE.push([x2, y2]);
}
//===========================放置食物==============================
function setFood(){
  do{
    FOODX = SIZE * Math.floor(Math.random() * MAXWIDTH / SIZE);
    FOODY = SIZE * Math.floor(Math.random() * MAXHEIGHT / SIZE);
  }while(foodInSnake());
  CTX.fillStyle = "red";
  CTX.fillRect (FOODX, FOODY, SIZE, SIZE);
}
function foodInSnake(){
  for (var i = 0; i < SNAKE.length; i++) {
    if(FOODX == SNAKE[i][0] && FOODY == SNAKE[i][1]){
      return true;
    }
  }
  return false;
}
//========================================移动一格===========================
function moveIn(x, y){
  CTX.fillStyle = "black";
  CTX.fillRect(x, y, SIZE, SIZE);//重画蛇头  
  //把新蛇头添加到 SNAKE 数组
  var newSnake = [[x, y]];
  SNAKE = newSnake.concat(SNAKE);

  if(false == eatFood()){//如果没吃到食物，减少一格蛇尾  
    var snakeTail = SNAKE.pop();//获得蛇尾位置
    CTX.clearRect(snakeTail[0], snakeTail[1], SIZE, SIZE);//去掉蛇尾  
  }
}
function eatFood(){
  if(HEADX == FOODX && HEADY == FOODY){
    CTX.fillStyle = "block";
    CTX.fillRect (FOODX, FOODY, SIZE, SIZE);

    setFood();
    SCORE++;
    //$("#score").text(SCORE);
    document.getElementById("score").innerHTML = SCORE;
    return true;
  }
  return false;
}

  </script>
</html>

Copy after login

Rendering:

Things:

function newgame(){
  重置蛇和分数的数据；
  清除interval；
  初始化画布；
  画一条蛇；
  放置食物；
  使用定时器（setInterval）使蛇移动（move函数）；
}
function move(){
  根据方向改变蛇头下一格将要到达的位置；
  判断游戏是否结束，以及显示结束的原因（包含输赢）；
  蛇移动一格（moveIn函数）；
}
对键盘的方向键作监控，当改变方向时，修改全局变量DIR的值（用于存储方向）；
function moveIn(){
  在蛇头的前一格增加一格作为新的蛇头，并将蛇头的坐标作为第一个元素加入到代表蛇的数组中；
  if(没吃到食物){
    删除一格蛇尾，在画布中做相应改变；
  }
}

Copy after login

It should be noted that if you need to set the width and height of the canvas in JS, it is slightly different from setting other CSS properties.

CANVAS.width = MAXWIDTH;CANVAS.height = MAXHEIGHT;

The editor has also prepared exciting topics for you: A summary of classic JavaScript games

The above is the entire content of this article. I hope it will be helpful to everyone in learning javascript programming.