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Native JavaScript Realizes Snake Game

  • 2021-09-12 00:11:02
  • OfStack

This article example for everyone to share the JavaScript implementation of the snake game specific code, for your reference, the specific content is as follows

1. HTML part, there are very few things 


<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title> Greedy snake </title>
 <style>
 *{
  margin: 0px;
  padding: 0px;
 }
 td{
  border-radius: 30%;
 }
 </style>
 
</head>
<body>
 <script type="text/javascript" src="./snake.js"></script>
</body>
</html>

2. JavaScript section 


var arrayBox = new Array(); //  Store cells 
var arraySnake = new Array(); //  Store snakes  
var food; //  Food 
var snakeHead; //  Snake head 
var key = true; //  Determine whether the page needs initialization 
var timekey; //  Motion timer constant 

function newGame() {
 bgInit();
 arrayBoxInit();
 initSnake();
 randomFood();
}

newGame();
document.onclick = function () {
 if (key) {
  gameStart(arraySnake);
  key = false;
 }
}



//  Initializes the cell array of the record 
function arrayBoxInit() {
 for (var y = 0; y < 20; y++) {
  arrayBox[y] = new Array();
  for (var x = 0; x < 20; x++) {
   arrayBox[y][x] = 0;
  }
 }
}

//  Background initialization 
function bgInit() {
 var table = document.createElement("table");
 table.style = "border-spacing:0px; border:1px solid #3c3c3c;margin:10% auto";
 for (var y = 0; y < 20; y++) {
  var tr = document.createElement("tr");
  for (var x = 0; x < 20; x++) {
   var td = "<td class='box-" + y + "-" + x + "' style='width: 20px; height: 20px;'></td>";
   tr.innerHTML += td;
  }
  table.appendChild(tr);
 }
 document.body.insertBefore(table, document.getElementsByTagName("script")[0]);
}

//  Initialization snake 
function initSnake() {
 var x = Math.floor(Math.random() * 20);
 var y = Math.floor(Math.random() * 20);
 var initA = document.getElementsByClassName("box-" + y + "-" + x)[0];
 snakeHead = initA; // Snake head 
 var b = initBFn(x, y);
 var initB = document.getElementsByClassName(b)[0];
 arraySnake.push(initB);
 arraySnake.push(initA);
 initA.style.backgroundColor = "#9c9c9c";
 initB.style.backgroundColor = "#9c9c9c";
 arrayBox[y][x] = 1;
 arrayBox[b.split("-")[1]][b.split("-")[2]] = 1;
}

//  Initialize snake body 
function initBFn(x, y) {
 if (x != 19 && x != 0) {
  if (y != 19 && y != 0) {
   if (Math.random() > 0.5) {
    if (Math.random() > 0.5) {
     return "box-" + y + "-" + (x + 1);
    } else {
     return "box-" + y + "-" + (x - 1);
    }
   } else {
    if (Math.random() > 0.5) {
     return "box-" + (y + 1) + "-" + x;
    } else {
     return "box-" + (y - 1) + "-" + x;
    }
   }
  } else if (y == 0) {
   if (Math.random() > 0.5) {
    return "box-0-" + (x + 1);
   } else {
    return "box-0-" + (x - 1);
   }
  } else if (y == 19) {
   if (Math.random() > 0.5) {
    return "box-19-" + (x + 1);
   } else {
    return "box-19-" + (x - 1);
   }
  }
 } else if (x == 0) {
  if (y != 19 && y != 0) {
   if (Math.random() > 0.5) {
    return "box-" + (y + 1) + "-0";
   } else {
    return "box-" + (y - 1) + "-0";
   }
  } else if (y == 0) {
   if (Math.random() > 0.5) {
    return "box-1-0";
   } else {
    return "box-0-1";
   }
  } else if (y == 19) {
   if (Math.random() > 0.5) {
    return "box-18-0";
   } else {
    return "box-19-1";
   }
  }
 } else if (x == 19) {
  if (y != 19 && y != 0) {
   if (Math.random() > 0.5) {
    return "box-" + (y + 1) + "-19";

   } else {
    return "box-" + (y - 1) + "-19";
   }
  } else if (y == 0) {
   if (Math.random() > 0.5) {
    return "box-1-19";
   } else {
    return "box-0-18";
   }
  } else if (y == 19) {
   if (Math.random() > 0.5) {
    return "box-18-19";
   } else {
    return "box-19-18";
   }
  }
 }
}

//  Randomly produce food food 
function randomFood() {
 var x = Math.floor(Math.random() * 20);
 var y = Math.floor(Math.random() * 20);
 if (!arrayBox[y][x]) {
  document.getElementsByClassName("box-" + y + "-" + x)[0].style = "background-color:#9c9c9c;border-radius:50%";
  arrayBox[y][x] = 1;
  food = document.getElementsByClassName("box-" + y + "-" + x)[0];
 } else {
  addSnakeLength();
 }
}

//  Start the game 
function gameStart(arraySnake) {
 var Ax = arraySnake[1].className.split("-")[2];
 var Ay = arraySnake[1].className.split("-")[1];
 var Bx = arraySnake[0].className.split("-")[2];
 var By = arraySnake[0].className.split("-")[1];
 if (Ay == By) {
  if (Ax > Bx) {
   moveRight();
  } else {
   moveLeft()
  }
 } else {
  if (Ay > By) {
   moveDown()
  } else {
   moveUp()
  }
 }
}


//  Initialize movement, (direction: right, left, up and down) 
function moveRight() {
 timekey = setInterval(function () {
  var nextBox = document.getElementsByClassName("box-" + arraySnake[arraySnake.length - 1].className.split("-")[1] + "-" + (parseInt(arraySnake[arraySnake.length - 1].className.split("-")[2]) + 1))[0];
  if (nextBox) {
   arrayBox[arraySnake[arraySnake.length - 1].className.split("-")[1]][(parseInt(arraySnake[arraySnake.length - 1].className.split("-")[2]) + 1)] = 1;
   nextBox.style.backgroundColor = "#9c9c9c";
   arraySnake.push(nextBox);
   arrayBox[arraySnake[0].className.split("-")[1]][arraySnake[0].className.split("-")[2]] = 0;
   arraySnake[0].style.backgroundColor = "#fff";
   arraySnake.shift();
   eatFood();
  }
 }, 200);
}

function moveLeft() {
 timekey = setInterval(function () {
  var nextBox = document.getElementsByClassName("box-" + arraySnake[arraySnake.length - 1].className.split("-")[1] + "-" + (parseInt(arraySnake[arraySnake.length - 1].className.split("-")[2]) - 1))[0];
  if (nextBox) {
   arrayBox[arraySnake[arraySnake.length - 1].className.split("-")[1]][(parseInt(arraySnake[arraySnake.length - 1].className.split("-")[2]) - 1)] = 1;
   nextBox.style.backgroundColor = "#9c9c9c";
   arraySnake.push(nextBox);
   arrayBox[arraySnake[0].className.split("-")[1]][arraySnake[0].className.split("-")[2]] = 0;
   arraySnake[0].style.backgroundColor = "#fff";
   arraySnake.shift();
   eatFood();
  }
 }, 200);
}

function moveUp() {
 timekey = setInterval(function () {
  var nextBox = document.getElementsByClassName("box-" + (parseInt(arraySnake[arraySnake.length - 1].className.split("-")[1]) - 1) + "-" + arraySnake[arraySnake.length - 1].className.split("-")[2])[0];
  if (nextBox) {
   arrayBox[(parseInt(arraySnake[arraySnake.length - 1].className.split("-")[1]) - 1)][arraySnake[arraySnake.length - 1].className.split("-")[2]] = 1;
   nextBox.style.backgroundColor = "#9c9c9c";
   arraySnake.push(nextBox);
   arrayBox[arraySnake[0].className.split("-")[1]][arraySnake[0].className.split("-")[2]] = 0;
   arraySnake[0].style.backgroundColor = "#fff";
   arraySnake.shift();
   eatFood();
  }
 }, 200);
}

function moveDown() {
 timekey = setInterval(function () {
  var nextBox = document.getElementsByClassName("box-" + (parseInt(arraySnake[arraySnake.length - 1].className.split("-")[1]) + 1) + "-" + arraySnake[arraySnake.length - 1].className.split("-")[2])[0];
  if (nextBox) {
   arrayBox[(parseInt(arraySnake[arraySnake.length - 1].className.split("-")[1]) + 1)][arraySnake[arraySnake.length - 1].className.split("-")[2]] = 1;
   nextBox.style.backgroundColor = "#9c9c9c";
   arraySnake.push(nextBox);
   arrayBox[arraySnake[0].className.split("-")[1]][arraySnake[0].className.split("-")[2]] = 0;
   arraySnake[0].style.backgroundColor = "#fff";
   arraySnake.shift();
   eatFood();
  }
 }, 200);
}

//  Keyboard operation turning 
document.addEventListener("keydown", function (e) {
 if (e.code == "ArrowDown") {
  turnDown();
 } else if (e.code == "ArrowUp") {
  turnUp();
 } else if (e.code == "ArrowLeft") {
  turnLeft();
 } else if (e.code == "ArrowRight") {
  turnRight();
 }
}, false);

//  Downturn 
function turnDown() {
 if (arraySnake[arraySnake.length - 1].className.split("-")[1] == arraySnake[arraySnake.length - 2].className.split("-")[1]) {
  clearInterval(timekey);
  moveDown();
 }
}
//  Downturn 
function turnUp() {
 if (arraySnake[arraySnake.length - 1].className.split("-")[1] == arraySnake[arraySnake.length - 2].className.split("-")[1]) {
  clearInterval(timekey);
  moveUp();
 }
}
//  Turn left 
function turnLeft() {
 if (arraySnake[arraySnake.length - 1].className.split("-")[2] == arraySnake[arraySnake.length - 2].className.split("-")[2]) {
  clearInterval(timekey);
  moveLeft();
 }
}
//  Turn right 
function turnRight() {
 if (arraySnake[arraySnake.length - 1].className.split("-")[2] == arraySnake[arraySnake.length - 2].className.split("-")[2]) {
  clearInterval(timekey);
  moveRight();
 }
}
//  Snakes eat food 
function eatFood() {
 var temp = food;
 if (arrayBox[food.className.split("-")[1]][food.className.split("-")[2]] == 0) {
  randomFood();
  addSnakeLength(temp);
 }
}
//  Increase the length at the tail of the snake 
function addSnakeLength(temp) {
 arraySnake.unshift(temp);
}

Knock down the whole process alone, knock for more than two hours, the basic functions have been realized, because there is no reference to anything, so there are many, many places that need to be optimized, please like it

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