javascript强化教程 - 六步实现贪食蛇
1.首先创建div 并且给div加样式
<div id="pannel" style="width: 500px;height: 500px;z-index: 1;opacity: 0.5"></div>
给
2.创建地图
document.write("<table cellspacing='0px'>");
for (var i = 0; i < 10; i++) {... }
document.write("</table>");3.调用createNode函数创建块
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var pannel = document.getElementById("pannel");
function createNode(type) {... } //根据type创建块（0头部 1食物 2身体） //申请一些变量以便以后调用
var allNode = new Array();//存所有吃到的身体
var fooldNode = null;//指向食物a
var headNode = null;//指向头部b
headNode = createNode(0);//创建头部A
headNode.value = 39;//给头部一个方向 37左 38上 39右 40下
fooldNode = createNode(1);//创建食物B4.定时器function moveNode() {...};setInterval(moveNode, 500);启动定时器
5.
document.onkeydown = function () {通过
event.keyCode改变headNode.value
实现用户按键改变蛇头自动移动的方向}6.核心逻辑
在第4中的 function moveNode() {...}; 定时执行此函数
实现了：1.移动所有身体
2.移动蛇头
3.创建新块并且 新块在蛇尾产生，方向与蛇尾相同
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实现源码
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
* {
padding: 0;
margin: 0;
}
td {
width: 48px;
height: 48px;
border: solid 1px darkorange;
}
div {
position: absolute;
width: 50px;
height: 50px;
}
</style> </head> <body> <div id="pannel" style="width: 500px;height: 500px;z-index: 1;opacity: 0.5"></div> <script>
document.write("<table cellspacing='0px'>");
for (var i = 0; i < 10; i++) {
document.write("<tr>");
for (var j = 0; j < 10; j++) {
document.write("<td></td>");
}
document.write("</tr>");
}
document.write("</table>");
//创建头部
var pannel = document.getElementById("pannel");
function createNode(type) { var div = document.createElement("div");
pannel.appendChild(div); div.style.left = parseInt(Math.random() * 10) * 50 + "px";
div.style.top = parseInt(Math.random() * 10) * 50 + "px"; switch (type) {
case 0: div.style.background = "red";//头
break;
case 1: div.style.background = "blue";//食物
break;
case 2: div.style.background = "yellow";//身体
break;
} return div; } var allNode = new Array();
var fooldNode = null;
var headNode = null; headNode = createNode(0); headNode.value = 39;
fooldNode = createNode(1); function moveNode() { //移动所有身体
if (allNode.length > 0) {
for (var n = allNode.length - 1; n >= 0; n--) {
switch (parseInt(allNode[n].value)) { case 37:
allNode[n].style.left = parseInt(allNode[n].style.left) - 50 + "px";
break; case 38:
allNode[n].style.top = parseInt(allNode[n].style.top) - 50 + "px";
break; case 39:
allNode[n].style.left = parseInt(allNode[n].style.left) + 50 + "px";
break; case 40:
allNode[n].style.top = parseInt(allNode[n].style.top) + 50 + "px";
break; } if(n>0){
allNode[n].value = allNode[n-1].value; }else {
allNode[n].value = headNode.value; } } }
var px = parseInt(headNode.style.left);
var py = parseInt(headNode.style.top); switch (headNode.value) { case 37:
headNode.style.left = px - 50 + "px"; break; case 38:
headNode.style.top = py - 50 + "px";
break; case 39: headNode.style.left = px + 50 + "px";
break; case 40:
headNode.style.top = py + 50 + "px"; break; }
//碰撞检测
if (headNode.style.left == fooldNode.style.left &&
headNode.style.top == fooldNode.style.top) { var newbody = createNode(2);
var lastbody = null; if (allNode.length == 0) {
lastbody = headNode; } else {
lastbody = allNode[allNode.length - 1]; }
newbody.value = lastbody.value; //
lastbody.style.left = parseInt(lastbody.style.left)-50+"px";
switch (parseInt(lastbody.value)) {
case 37:
newbody.style.left = parseInt(lastbody.style.left) + 50 + "px";
newbody.style.top = lastbody.style.top;
break;
case 38:
newbody.style.top = parseInt(lastbody.style.top) + 50 + "px";
newbody.style.left = lastbody.style.left;
break;
case 39:
newbody.style.left = parseInt(lastbody.style.left) - 50 + "px";
newbody.style.top = lastbody.style.top;
break;
case 40: newbody.style.top = parseInt(lastbody.style.top) - 50 + "px";
newbody.style.left = lastbody.style.left; break; }
allNode.push(newbody); fooldNode.style.left = parseInt(Math.random() * 10) * 50 + "px";
fooldNode.style.top = parseInt(Math.random() * 10) * 50 + "px"; }//碰撞end }
setInterval(moveNode, 500); document.onkeydown = function () { switch (event.keyCode) {
case 37: headNode.value = 37; break;
case 38: headNode.value = 38; break;
case 39: headNode.value = 39; break;
case 40: headNode.value = 40; break; }
} </script>
</body>
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