30行到17行原生js写(变色)贪吃蛇

相比于网上很火的20行贪吃蛇,这个版本主要是用二维数组改写增加了可读性, 同时也只有1100个字符原版900个字符,不像某篇宣称17行的博客,有1400个字符

环境是ES6

相较于20行版本

此版本用的是二维数组,而不是一维,因此更好调试,可读性也更强,并且没有3目运算符
这个版本没有BUG,原版: 蛇身长为4时,也会碰到自己;大部分博文都会犯这个小错误
按谷歌的说法能省的标签的都省了

https://google.github.io/styleguide/htmlcssguide.html#Optional_Tags

2维数组版本和注释^{1100 char 26 line}

<!DOCTYPE html>
<canvas id="1" width="400" height="400" style="border: 1px solid "></canvas>
<script>
ctx = document.getElementById("1").getContext("2d") //CanvasRenderingContext2D inferface
let Len = 10, dir = 2, dirNow ; //dirNow 后面解释
food = [3, 0]; Snake = [[0, 0], [1, 0]] //食物的坐标,蛇身的坐标用Snake数组记录
Map = {'0,0':'#52a', '1,0':'#52a'} //用来记录绘图颜色的地图
dirMat = [[-1, 0], [0, -1], [1, 0], [0, 1]] //方向矩阵
pairEq = ((p1, p2) => p1[0] == p2[0] && p1[1] == p2[1]) //检测两数对是否相等的函数
document.onkeydown = e =>{
if (37 <= e.keyCode == e.keyCode < 41 && dirNow != ( (e.keyCode - 35) % 4) ) //确定是方向键并且保证方向与当前运动方向相反
dir = e.keyCode -37
}
!function () {
Head = Snake[Snake.length-1].map((x, i) => x + dirMat[dirNow=dir][i]); //得到头部接下来的移动位置
if (!pairEq(Head, food))
Map[Snake.shift()]='#fff' //必须先删尾巴,才能加入头部,吃没吃到食物是唯一判断标准
if (Snake.some(x=>pairEq(x,Head)) || !Head.every(x => 0<=x == x < Len)) //判断蛇头是否撞到蛇身或墙壁
return document.write("Game Over") //这样调用document.write会把页面全部清空
Snake.push(Head); //可以加入头部
while (Snake.some(x => pairEq(x, food))) //加入新头后, 生成食物更方便
food = [0|Math.random() * Len, 0|Math.random() * Len]; //因为js没有整形的概念, ~~ 现在相当于向原点舍去
Map[Head] = '#52a' ; Map[food] = '#ad5'
for( k in Map){
ctx.fillStyle= Map[k]
ctx.fillRect(parseInt(k[0])*40,parseInt(k[2])*40,40,40) //e.g. k="1,3",也因此地图大小限制为10
}
setTimeout(arguments.callee, 100); //100ms后调用此函数一次
}()
</script>

七彩蛇^{1100char 22line}||原20行版本^{900 char 19line}

<!DOCTYPE html>
<canvas id="1" width="400" height="400" style="border: 1px solid " ></canvas>
<script>
ctx = document.getElementById("1").getContext("2d")
let Len = 10, dir = 2, dirNow ;food = [3, 0]; Snake = [[0, 0], [1, 0]]
Map = {'0,0':'fff', '1,0':'fff'}
dirMat = [[-1, 0], [0, -1], [1, 0], [0, 1]]
pairEq = ((p1, p2) => p1[0] == p2[0] && p1[1] == p2[1])
document.onkeydown = e =>{
if (37 <= e.keyCode == e.keyCode < 41 && dirNow != ( (e.keyCode - 35) % 4) ) dir = e.keyCode -37
}
!function () {
Head = Snake[Snake.length-1].map((x, i) => x + dirMat[dirNow=dir][i]);
if (!pairEq(Head, food)) Map[Snake.shift()]='0'
if (Snake.some(x=>pairEq(x,Head)) || !Head.every(x => 0<=x == x < Len))
return document.write("Game Over")
Snake.push(Head);
while (Snake.some(x => pairEq(x, food))) food = [0|Math.random() * Len, 0|Math.random() * Len];
Map[Head] = Map[food] = 'fff'
for( k in Map){
ctx.fillStyle='#'+(0xfff- (0|parseInt(Map[k],16)*Math.random())).toString(16)
ctx.fillRect(parseInt(k[0])*40,parseInt(k[2])*40,46,43)
}
setTimeout(arguments.callee, 100);
}()
</script>

<!doctype html>
<canvas id="can" width="400" height="400" style="background: Black"></canvas>
<script>
var sn = [ 42, 41 ], dz = 43, fx = 1, n, ctx = document.getElementById("can").getContext("2d");
function draw(t, c) {
ctx.fillStyle = c;
ctx.fillRect(t % 20 * 20 + 1, ~~(t / 20) * 20 + 1, 18, 18);
}
document.onkeydown = function(e) {
fx = sn[1] - sn[0] == (n = [ -1, -20, 1, 20 ][(e || event).keyCode - 37] || fx) ? fx : n
};
!function() {
sn.unshift(n = sn[0] + fx);
if (sn.indexOf(n, 1) > 0 || n<0||n>399 || fx == 1 && n % 20 == 0 || fx == -1 && n % 20 == 19)
return alert("GAME OVER");
draw(n, "Lime");
if (n == dz) {
while (sn.indexOf(dz = ~~(Math.random() * 400)) >= 0);
draw(dz, "Yellow");
} else draw(sn.pop(), "Black");
setTimeout(arguments.callee, 130);
}();
</script>

二维数组再简化^{860char 18line}||一维数组再简化^{700char 17line}

<!DOCTYPE html>
<canvas id="1" width="400" height="400" style="border: 1px solid "></canvas>
<script>
let d = 2, dN,f = [3, 0],S = [[0, 0]],M = {},C = document.getElementById("1").getContext("2d")
Eq = ((p1, p2) => p1[0] == p2[0] && p1[1] == p2[1]);
document.onkeydown = e => {a = e.keyCode - 37;if (0 <= a == a < 4 && dN != ((a + 2) % 4)) d = a}
!function () {
H = S[S.length - 1].map((x, i) => x + [[-1, 0], [0, -1], [1, 0], [0, 1]][dN = d][i])
if (!Eq(H, f)) M[S.shift()] = '#fff'
if (S.some(x => Eq(x, H)) || !H.every(x => 0 <= x == x < 10))
return document.write("Game Over")
S.push(H)
while (S.some(x => Eq(x, f)))
f = [0 | Math.random() * 10, 0 | Math.random() * 10]
M[H] = '#52a';M[f] = '#ad5'
for (k in M) {
C.fillStyle = M[k]
C.fillRect(parseInt(k[0]) * 40, parseInt(k[2]) * 40, 40, 40)
}
setTimeout(arguments.callee, 100)
}()
</script>

<!DOCTYPE html>
<canvas id="1" width="400" height="400"></canvas>
<script>
let dir=1,food=3,snk=[1,0], ctx=document.getElementById("1").getContext("2d")
document.onkeydown=e=>{
dir =((snk[0]-snk[1]==-(tmp = [-1,-10,1,10][e.keyCode-37]||dir))?dir:tmp
}
!function () {
snk.unshift(Head = snk[0] + dir)
if(Head!=food) snk.pop()
else while(snk.includes(food=0|Math.random()*10*10)) ;
if( snk.indexOf(Head,1)!=-1||(dir ==1&& Head%10==0)||(dir==-1&& Head%10==9)||Head<0||Head>=100) {
return document.write("Game Over")
}
for(let i =0 ;i< 100 ; i++){
ctx.fillStyle = '#0'+(food===i)*9910+snk.includes(i)*1990
ctx.fillRect(i%10*40,(i-i%10)*4, 40,40)
}
setTimeout(arguments.callee, 100);
}()
</script>

几个常见问题

蛇尾应该比蛇头先消失,蛇头应该比食物先生成,
蛇不能走当前相反的方向,可以用长度为4的蛇进行测试

30行到17行原生js写(变色)贪吃蛇

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