怀念经典-JS小游戏-贪吃蛇

<script>
   
    class Map{
        constructor(){
            this.w = 800;
            this.h = 400;
            this.c = "#ccc";
            this.createEle();
        }
        createEle(){
            this.mapEle = document.createElement("div");
            this.mapEle.style.cssText = `width:${this.w}px;height:${this.h}px;background:${this.c};margin:0 auto;position:relative;border:solid 10px black;`;
            document.body.appendChild(this.mapEle);
        }
    }
    class Food{
        constructor(){
            this.w = 20;
            this.h = 20;
            this.c = "red";
            this.x = 0;
            this.y = 0;
            this.createEle();
        }
        createEle(){
            this.foodEle = document.createElement("div");
            this.foodEle.style.cssText = `width:${this.w}px;height:${this.h}px;background:${this.c};
position:absolute;left:${this.x * this.w}px;top:${this.y * this.h}px;`;
            m.mapEle.appendChild(this.foodEle);
        }
        randomPos(){
            this.x = random(0,(m.w-this.w) / this.w);
            this.y = random(0,(m.h-this.h) / this.h);
            this.foodEle.style.left = this.x * this.w + "px";
            this.foodEle.style.top = this.y * this.h + "px";
        }
    }
    class Snake{
        constructor(){
            this.w = 20;
            this.h = 20;
            this.body = [{
                ele:null,
                x:4,
                y:3,
                c:randomColor()
            },{
                ele:null,
                x:3,
                y:3,
                c:randomColor()
            },{
                ele:null,
                x:2,
                y:3,
                c:randomColor()
            }];

            this.d = "right";

            this.createEle();
        }
        createEle(){
            for(var i=0;i<this.body.length;i++){
                if(!this.body[i].ele){
                    this.body[i].ele = document.createElement("div");
                    m.mapEle.appendChild(this.body[i].ele);
                }
                this.body[i].ele.style.cssText = `width:${this.w}px;height:${this.h}px;background:${this.body[i].c};
position:absolute;left:${this.body[i].x * this.w}px;top:${this.body[i].y * this.h}px;`;
            }
            this.body[0].ele.innerHTML = "0";

            setTimeout(()=>{
                this.move();
            },300);
        }
        move(){
            for(var i=this.body.length-1; i>0; i--){
                this.body[i].x = this.body[i-1].x;
                this.body[i].y = this.body[i-1].y;
            }
            switch(this.d){
                case "left":
                    this.body[0].x -= 1;
                    break;
                case "right":
                    this.body[0].x += 1;
                    break;
                case "top":
                    this.body[0].y -= 1;
                    break;
                case "bottom":
                    this.body[0].y += 1;
                    break;
            }
            
            if(this.body[0].x < 0 || this.body[0].y < 0 || this.body[0].x > ((m.w-this.w) / this.w) || this.body[0].y > ((m.h-this.h) / this.h)){
                alert("撞墙了");
                return;
            }

            if(this.body[0].x === f.x && this.body[0].y === f.y){
                this.body.push({
                    ele:null,
                    x:this.body[this.body.length-1].x,
                    y:this.body[this.body.length-1].y,
                    c:randomColor()
                })
                f.randomPos();
            }

            for(var i=1;i<this.body.length;i++){
                if(this.body[0].x == this.body[i].x && this.body[0].y == this.body[i].y){
                    alert("撞到自己了");
                    return;
                }
            }

            this.createEle();
        }
        direct(type){
           
            switch(type){
                case 37:
                    if(this.d === "right") break;
                    this.d = "left";
                    break;
                case 38:
                    if(this.d === "bottom") break;
                    this.d = "top";
                    break;
                case 39:
                    if(this.d === "left") break;
                    this.d = "right";
                    break;
                case 40:
                    if(this.d === "top") break;
                    this.d = "bottom";
                    break;
            }
        }
    }

    function random(a,b){
        return Math.round(Math.random()*(a-b)+b)
    }
    function randomColor(){
        return `rgb(${random(0,255)},${random(0,255)},${random(0,255)})`
    }

    var m = new Map();
    
    var f = new Food();
   
        f.randomPos();

    var s = new Snake();
    document.onkeydown = function(eve){
        var e = eve || window.event;
        var code = e.keyCode || e.which;
        s.direct(code);
    }

</script>