Writing Snake Game with Native JS

This article shares the specific code of writing a snake game in js for your reference. The specific content is as follows

I just finished learning js and imitated the tutorial to write my own js native applet.

HTML Part

<!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>Document</title>
    <link rel="stylesheet" href="./css/index.css" >
</head>
<body>
    <div class="content">
     <!-- Game start button-->
        <div class="btn startBtn"><button></button></div>
        <!-- Snake Body -->
        <div id="snakeWrap"></div>
    </div>
    <!-- Import external js files-->
    <script src="./js/index.js"></script>
</body>
</html>

CSS part

/* Overall style */
.content{
    width: 640px;
    height: 640px;
    margin: 100px auto;
    position: relative;
}
 .btn{
    width: 100%;
    height: 100%;
    position: absolute;
    left: 0;
    top: 0;
    background-color: rgba(0, 0, 0, 0.3);
    z-index: 2;
}

.btn button{
    background: none;
    border: none;
    background-size: 100% 100%;

    cursor: pointer;
    outline: none;

    position: absolute;
    left: 50%;
    top: 50%;
}

.startBtn button{
    width: 200px;
    height: 80px;
    background: url(../images/Snipaste_2021-05-08_08-52-45.png) no-repeat;
    background-size: contain;
    margin-left: -100px;
    margin-top: 222px;
}

#snakeWrap{
    width: 600px;
    height: 600px;
    background: #73aad4;
    border: 20px solid #13649c;
    position: relative;
}

.snakeHead{
    background-color: yellowgreen;
    border-radius: 50%;
}

.snakeBody{
    background-color: black;
    border-radius: 50%;
}

.food{
    background-color: red;
    border-radius: 50%;
}

js part

var sw = 20, //width of a block sh = 20, //width of a block tr = 30, //number of rows td = 30; //number of columns var snake = null, //generate snake instance food = null; //generate food instance game = null; //create game instance //create and delete blocks when treating the whole as a small block moving (all subsequent blocks will be called)
// Square constructor function Square(x,y,classname){ //Corresponding to the three snake styles in CSS (snake head, snake body, snake tail)
    this.x = x * sw;
    this.y = y * sh;
    this.class = classname;
    this.viewContent = document.createElement('div');
    this.viewContent.className = this.class; //Add the corresponding css style to the created div this.parent = document.getElementById('snakeWrap');    
}

//Create the create method on the prototype chain of the block constructor to determine the specific information of the new div //this points to Square
Square.prototype.create = function(){
    this.viewContent.style.position = 'absolute';
    this.viewContent.style.width = sw + 'px';
    this.viewContent.style.height = sh + 'px';
    this.viewContent.style.left = this.x + 'px';
    this.viewContent.style.top = this.y + 'px';

    this.parent.appendChild(this.viewContent); //Add the newly created div to the page}

//Create a remove method on the prototype chain of the block constructor to delete the block when moving Square.prototype.remove = function(){
    this.parent.removeChild(this.viewContent);
}

//Snake function Snake(){
    this.head = null; //Store the snake's head information this.tail = null; //Store the snake's tail information this.pos = []; //Store the position of each block on the snake this.directionNum = { //Store the direction the snake is walking left : {
            x : -1,
            y : 0
        },
        right : {
            x : 1,
            y : 0
        },
        up : {
            x : 0,
            y : -1
        },
        down : {
            x : 0,
            y : 1
        }
    }
}

//this points to Snake
Snake.prototype.init = function(){ // Initialization // Create snake head var snakeHead = new Square(2,0,'snakeHead');
    snakeHead.create();
    this.head = snakeHead;
    this.pos.push([2,0]); //Store snake head information // Create snake body 1
    var snakeBody1 = new Square(1,0,'snakeBody');
    snakeBody1.create();
    this.pos.push([1,0]); //Store snake body information // Create snake tail var snakeBody2 = new Square(0,0,'snakeBody');
    snakeBody2.create();
    this.tail = snakeBody2;
    this.pos.push([0,0]); /Store the confidence of the snake's tail//Form a linked list relationship//The relationship between the snake's head, body and tail snakeHead.last = null;
    snakeHead.next = snakeBody1;

    snakeBody1.last = snakeHead;
    snakeBody1.next = snakeBody2;

    snakeBody2.last = snakeBody1;
    snakeBody2.next = null;

    //Add a default direction to the right for the snake this.direction = this.directionNum.right;
}

// Get the element corresponding to the next position of the snake head (this points to Snake)
// Get the coordinates of the next point and store them in the nextPos array Snake.prototype.getNextPos = function(){
    var nextPos = [
        this.head.x/sw + this.direction.x, //this.direction.x, y The following will bind the direction to the keyboard event to determine the location of the next point this.head.y/sh + this.direction.y
    ]
    
    // The next point is yourself. The game ends when you collide with yourself var selfCollied = false;
    this.pos.forEach(function(value){ //forEach traverses the array and compares the two arrays to see if there are duplicate coordinates if (value[0] == nextPos[0] && value[1] == nextPos[1]){
            selfCollied = true;
        }
    })
 
 //The game ends when you hit yourself if (selfCollied) {
        this.、
        .die.call(this);
        return;
    }

    // The next point is the wall game end if (nextPos[0] > 29 || nextPos[0] < 0 || nextPos[1] > 29 || nextPos[1] < 0) {
        this.strategies.die.call(this);
        return;
    }

    // The next point is food to eat if(food && food.pos[0] == nextPos[0] && food.pos[1] == nextPos[1]){
        this.strategies.eat.call(this);
        return;
    }

    // The next point is nothing, so go this.strategies.move.call(this);
}


// What to do after a collision Snake.prototype.strategies = {
    move : function(format){ //The parameter is used to determine whether to delete the snake tail // Create a newbody and delete the snake head var newBody = new Square(this.head.x/sw,this.head.y/sh,'snakeBody')
        newBody.next = this.head.next;
        newBody.next.last = newBody;
        newBody.last = null;
        this.head.remove();
        newBody.create();

        // Create a new snake head var newx = this.head.x/sw + this.direction.x;
        var newy = this.head.y/sh + this.direction.y;
        var newHead = new Square(newx,newy,'snakeHead')
        newHead.next = newBody;
        newBody.last = newHead;
        newHead.last = null;
        newHead.create();

        // Update the coordinates of the snake body this.pos.splice(0,0,[newx,newy]);
        this.head = newHead;

        //If it is false, then eat if(!format){
            this.tail.remove();
            this.tail = this.tail.last;

            this.pos.pop();
        }
    },
    eat : function(){
        this.strategies.move.call(this,true);
        game.score++;
        createFood();
    },
    die : function(){
        game.over();
    }
}


snake = new Snake();


// Create food function createFood(){
    // Food cube coordinates var x = null;
    var y = null;

    var include = true;
    while(include){
        x = Math.round(Math.random()*(td - 1));
        y = Math.round(Math.random()*(tr - 1));

        snake.pos.forEach(function(value){
            if(x != value[0] && y != value[1]){
                include = false;
            }
        });
    }
    // Generate food food = new Square(x,y,'food');
    food.pos = [x,y];

    var foodDom = document.querySelector('.food');
    if(foodDom){
        foodDom.style.left = x * sw + 'px';
        foodDom.style.top = y * sh + 'px';
    }else{
        food.create();
    }
}



// Create game logic function Game(){
    this.timer = null;
    this.score = 0;
}

Game.prototype.init = function(){
    snake.init();
    createFood();
 //The previous e.keycode e.which here has been disabled. Use e.key
    window.addEventListener('keydown',function(e){
        if(e.key == 'ArrowLeft' && snake.direction != snake.directionNum.right){
            snake.direction = snake.directionNum.left;
        }else if(e.key == 'ArrowUp' && snake.direction != snake.directionNum.down){
            snake.direction = snake.directionNum.up;
        }else if(e.key == 'ArrowRight' && snake.direction != snake.directionNum.left){
            snake.direction = snake.directionNum.right;
        }else if(e.key == 'ArrowDown' && snake.direction != snake.directionNum.up){
            snake.direction = snake.directionNum.down;
        }
    });
    this.start();
}

Game.prototype.start = function(){
    this.timer = setInterval(function(){
        snake.getNextPos();
    },0.0000000000000001)
}

Game.prototype.over = function(){
    clearInterval(this.timer);
    alert('Your score is' + this.score);


    // The game returns to the initial state var snakeWrap = document.getElementById('snakeWrap');
    snakeWrap.innerHTML = '';

    snake = new Snake();
    game = new Game();

    var startBtnWrap = document.querySelector('.startBtn');
    startBtnWrap.style.display = 'block';
}

// Start the game game = new Game();
var startBtn = document.querySelector('.startBtn button');
startBtn.onclick = function(){
    startBtn.parentNode.style.display = 'none';
    game.init();
}

This is a simple little game. If you have any questions, please correct me.

The above is the full content of this article. I hope it will be helpful for everyone’s study. I also hope that everyone will support 123WORDPRESS.COM.

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