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JavaScript implementation of guessing number game example code
- 零下一度Original
- 2017-04-21 10:00:096053browse
This article mainly introduces the example code of js to implement a guessing game. It has a very good reference value. Let’s take a look with the editor.
See how many guesses you need to guess the correct number!
Rendering:
##The code is as follows:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>猜数字游戏</title>
<script type="text/javascript" charset="utf-8">
window.onload = newgame; //页面载入的时候就开始一个新的游戏
window.onpopstate = popState; //处理历史记录相关事件
var state, ui; //全局变量，在newgame()方法中会对其初始化
function newgame(playagain) {
ui = {
heading: null, //文档最上面的<h1>元素
prompt: null, //要求用户输入一个猜测数字
input: null, //用户输入猜测数字的地方
low: null, //可视化的三个表格单元格
mid: null, //猜测的数字范围
high: null,
};
//查询这些元素中每个元素的id
for(var id in ui) ui[id] = document.getElementById(id);
//给input字段定义一个事件处理程序函数
ui.input.onchange = handleGuess;
//生成一个随机的数字并初始化游戏状态
state = {
n: Math.floor(99 * Math.random())+1, //整数： 0 < n <100
low: 0, //可猜数字范围下限
high: 100, //可猜数字范围上限
guessnum: 0, //猜测的次数
guess: undefined //最后一次猜测
};
//修改文档内容来显示该初始状态
display(state);
if (playagain === true)save(state);
}
function save(state) {
if (!history.pushState) return; //如果pushState()方法没有定义，则什么也不做
//将一个保存的状态和url关联起来
var url = "#guess" + state.guessnum;
history.pushState(state, //要保存的状态对象
"", //状态标题：当前浏览器会忽视它
url); //状态URL：对书签是没有用的
}
//这是onpopstate的事件处理程序，用于恢复历史状态
function popState(event) {
if (event.state) {
//如果事件有一个状态对象，则恢复该状态
state = event.state; //恢复历史状态
display(state); //显示恢复的状态
}else{
history.replaceState(state, "", "#guess" + state.guessnum);
}
};
//每次猜测一个数字的时候，都会调用此事件处理程序
//此处理程序用于更新游戏的状态、保存游戏状态并显示游戏状态
function handleGuess() {
//从input字段中获取用户猜测的数字
var g = parseInt(this.value);
//如果该值是限定范围中的一个数字
if ((g > state.low) && (g < state.high)) {
//对应的更新状态
if (g < state.n) state.low =g;
else if (g > state.n) state.high = g;
state.guess = g;
state.guessnum++;
//在浏览器历史记录中保存新的状态
save(state);
//根据用户猜测情况来修改文档
display(state);
}else{
//无效的猜测：不保存状态
alert("请输入大于" + state.low + "和小于" + state.high);
}
}
//修改文档来显示游戏当前状态
function display(state) {
//显示文档的导航和标题
ui.heading.innerHTML = document.title ="我在想一个" + state.low + "到" + state.high + "之间的数字！";
//使用一个表格来显示数字的取值范围
ui.low.style.width = state.low + "%";
ui.mid.style.width = (state.high-state.low) + "%";
ui.high.style.width = (100-state.high) + "%";
//确保input字段是可见的、空的并且是聚焦的
ui.input.style.visibility = "visible";
ui.input.value = "";
ui.input.focus();
//根据用户最近猜测，设置提示
if (state.guess === undefined)
ui.prompt.innerHTML = "输入你的猜测：";
else if (state.guess < state.n)
ui.prompt.innerHTML = state.guess + "低了，再猜一次：";
else if (state.guess > state.n)
ui.prompt.innerHTML = state.guess + "高了，再猜一次：";
else {
//当猜对了的时候，就隐藏input字段并显示“再玩一次”按钮
ui.input.style.visibility = "hidden";
ui.heading.innerHTML = document.title = state.guess + "正确！";
ui.prompt.innerHTML = "你赢了 <button onclick='newgame(true)'>再玩一次</button>";
}
}
</script>
<style>
#prompt { font-size: 16pt;}
table { width: 90%; margin:10px; margin-left:5%;}
#low, #high { background-color:lightgray; height:1em; }
#mid { background-color:green;}
</style>
</head>
<body>
<h1 id="heading">我在想一个数字...</h1>
<table>
<tr>
<td id="low"></td>
<td id="mid"></td>
<td id="high"></td>
</tr>
</table>
<label id="prompt"></label>
<input id="input" type="text">
</body>
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