效果如图所示:

下面是核心代码
复制代码 代码如下:
GAME = {
//随机产生字母
randLetter: function() {
var arrLetter = new Array("A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W",
"X",
"Y", "Z");
//随机产生字母
var index = Math.floor(Math.random() * 26);
return arrLetter[index];
},
//随机字母颜色
randLetterColor: function() {
var arrLetterColor = new Array("Red", "Green", "#555", "Blue", "Black");
var index = Math.floor(Math.random() * 4);
return arrLetterColor[index];
},
//随机字母大小
randLetterSize: function() {
var arrLetterSize = new Array("12px", "16px", "20px", "24px", "28px", "32px", "36px", "40px");
var index = Math.floor(Math.random() * 7);
return arrLetterSize[index];
},
//创建DIV
divCreate: function(width, height, left, top, value) {
this.width = width;
this.height = height;
this.div = document.createElement("div");
this.div.style.width = width;
this.div.style.height = height;
this.div.style.left = left;
this.div.style.top = top;
this.div.innerText = value;
this.div.style.color = this.randLetterColor();
this.div.style.fontSize = this.randLetterSize();
this.div.style.lineHeight = this.div.style.height;
this.div.style.textAlign = "center";
this.div.style.fontWeight = "bold";
//this.div.style.border = "solid red 1px";
this.div.style.position = "relative";
document.getElementById("map").appendChild(this.div);
return this.div;
},
//DIV下落
divDown: function() {
var divTop = parseInt(this.div.style.top.slice(0, -2)); //字母方块的Top
var mapHeight = parseInt(document.getElementById("map").style.height.slice(0, -2));
//就消失
if (divTop < mapHeight - parseInt(this.height) + 20) {
this.div.style.top = divTop + 30;
//获取按键的值
document.onkeydown = function() {
//按键的字母是不是 等于 div的值
if (String.fromCharCode(event.keyCode) == GAME.div.innerText) {
document.getElementById("TextRecord").value = "正确";
GAME.div.style.display = "none";
clearInterval(GAME.timeCreateID);
GAME.divCreate(100, 100, Math.floor(Math.random() * 300), -30, GAME.randLetter());
}
else {
document.getElementById("TextRecord").value = "错误";
}
}
}
//到达底线就消失，之后再创建DIV
else {
this.div.style.display = "none";
GAME.divCreate(100, 100, Math.floor(Math.random() * 300), -30, this.randLetter());
}
},
timeCreateID: null,
timeDownID: null,
START: function() {
this.divCreate(100, 100, 200, -40, this.randLetter());
this.timeDownID = setInterval("GAME.divDown();", 1000);
document.getElementById('ButtonStart').disabled = 'disabled';
document.getElementById('ButtonStop').disabled = '';
},
STOP: function() {
if (this.timeDownID != null) {
clearInterval(this.timeDownID);
this.div.style.display = "none";
}
document.getElementById('ButtonStart').disabled = '';
document.getElementById('ButtonStop').disabled = 'disabled';
}

}

效果演示
Snmon转正题目 - -||| ，题目需求还要复杂100倍。。。 <p>暂时只实现了随机生成字母，已监听键盘，还未计算得分。</p> 得分：<input id="TextRecord" value="0" type="text" /> <input id="ButtonStart" onclick="GAME.START();" value="GAME START" type="button"><input id="ButtonStop" onclick="GAME.STOP();" value="GAME STOP" type="button">
[Ctrl+A 全选 注:引入外部Js需再刷新一下页面才能执行]