let timre = setInterval(start_snake,200);
let lis = document.getElementsByTagName("li");
function start_snake(){
let left=parseFloat(lis[0].style.left);
let top= parseFloat(lis[0].style.top);
switch (direction) {
case "left":left = (left-20);break;
case "up":top = (top-20);break;
case "right":left = (left+20);break;
case "down":top = (top+20);break;
default:;
}
if(left<0 || left>800-20 || top<0 || top>600-20){
window.clearInterval(timre);
alert("亲,您Game Over");
return;
}
for(var i=lis.length-1;i>0;i--){
lis[i].style.left = lis[i-1].style.left;
lis[i].style.top = lis[i-1].style.top;
}
lis[0].style.left = left+"px";
lis[0].style.top = top+"px";
if(left == food_left && top == food_top){
eat();
}
}
function eat() {
$("js_bg").removeChild($("foodDiv"));
js_food();
let li = document.createElement("li");
$("js_bg").appendChild(li);
}