function Snake(element) {

    this.width = 20

    this.height = 20

    //蛇身 位置 颜色

    this.body = [

        {x: 6, y: 4, bc: 'red'},

        {x: 5, y: 4, bc: 'blue'},

        {x: 4, y: 4, bc: 'blue'},

    ]

    this.direction = 'right'

    this.elemen = element

    //保存当前蛇

    this.arr = []

}

//吃食物

Snake.prototype.feed = function (food) {

    // 遇到食物 复制最后一个蛇身

    if (this.body[0].x * this.width === food.x && this.body[0].y * this.height === food.y) {

        let o = this.body[this.body.length - 1]

        let pro = {x: o.x, y: o.y, bc: o.bc}

        this.body.push(pro)

    }

}

Snake.prototype.remove = function () {

    for (let i = 0; i < this.arr.length; i++) {

        this.arr[i].parentNode.removeChild(this.arr[i])

    }

    this.arr = []

}

//蛇出现

Snake.prototype.show = function () {

    this.remove()

    //console.log(this.arr)

    for (let i = 0; i < this.body.length; i++) {

        let div = document.createElement('div')

        this.elemen.appendChild(div)

        div.style.width = this.width + 'px';

        div.style.height = this.height + 'px'

        div.style.position = 'absolute'

        div.style.backgroundColor = this.body[i].bc

        div.style.left = this.body[i].x * this.width + 'px'

        div.style.top = this.body[i].y * this.height + 'px'

        this.arr.push(div)

    }

}

//移动方法

Snake.prototype.udlr = function () {

    //蛇身移动 根据最后一个的位置等于上一个的位置

    for (let 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

    }

    // 边界

    let herfX = this.body[0].x * this.width >= this.elemen.offsetWidth - this.width || this.body[0].x * this.width <= 0

    let herfY = this.body[0].y * this.height >= this.elemen.offsetHeight - this.height || this.body[0].y * this.height <= 0

    if (herfX || herfY) {

        alert('完蛋')

        return

    }

    switch (this.direction) {

        case "right": {

            this.body[0].x += 1

            break;

        }

        case "letf": {

            this.body[0].x -= 1

            break;

        }

        case "up": {

            this.body[0].y -= 1

            break;

        }

        case "down": {

            this.body[0].y += 1

            break;

        }

    }

}