虽然写的不是很好，但 解释权以及版权仍然归13东倍所有！
<!DOCTYPE HTML>
<!DOCTYPE HTML>
<html>
<head>
<title>canvas-00</title>
<script>
window.onload=function(){
//alert("coming onload");
alert("游戏说明：在键盘上输入的字符与游戏下落的字符相同时，积分板加分，积分达到一定时，提示进入下一关，若字符落到底部，即游戏结束。点击按钮开始游戏吧！");
var game=new Game();
game.start();
}
function Game(){
//alert("coming Game()");
var
createChar=new Array();
//var scoreBoard=new Array();
var scoreBoard=new CreateScoreBoard();
for(var i=0;i<10;i++){
createChar[i]=new CreateChar();
//scoreBoard[i]=new CreateScoreBoard();
}
this.start=function(){
var time=setInterval(function(){
for(var i=0;i<10;i++){
createChar[i].clearContext();
//scoreBoard[i].clearScore();
}
for(var i=0;i<10;i++){
createChar[i].move();
createChar[i].show();
//scoreBoard[i].show();
if(createChar[i].return_y()>490){
clearInterval(time);
for(var i=0;i<10;i++){
createChar[i].clearContext();
}
alert("game over");
break;
}
}
scoreBoard.showScore();
},50);
document.onkeydown=keydown;
var jifen=200;
var pass=2;
function keydown(e){
var real=String.fromCharCode(e.which);
//alert(real);
for(var i=0;i<10;i++){
if(real==createChar[i].returnWords()){
//alert("zhong");
//scoreBoard[i].addScores();
scoreBoard.addScores();
//alert("00");
createChar[i].returnTOP();
if(scoreBoard.returnScore()==jifen){
jifen+=200;
alert("恭喜你，点击确定进入第"+(pass++)+"关！");
for(var i=0;i<10;i++){
createChar[i].returnTOP();
createChar[i].speed();
}
}
}
}
}
}
}
function CreateChar(){
//alert("coming CreateChar()");
var canvas;
var context;
var char_y=50;
//规定范围内取随机数 *（上限-下限+1）+下限
var char_x;
var words=new Array("A","B","C","D","E","F","G","H","I","J","K","L","N","M","O","P","Q","R","S","T","U","V","W","Z","X","Y");
var num;
var down=1;
function initChar(){
canvas=document.getElementById("myCanvas");
//alert("canvas--"+canvas);
context=canvas.getContext("2d");
//alert("context--"+context);
context.font="20pt 黑体";
num=parseInt(Math.random()*words.length);
char_x=parseInt(Math.random()*(680-20-1)+20);
context.fillText(words[num],char_x,char_y);
}
initChar();
this.move=function(){
char_y+=down;
}
this.show=function(){
context.font="20pt 黑体";
context.fillText(words[num],char_x,char_y);
}
this.clearContext=function(){
//alert("coming clearContext()");
return context.clearRect(0,0,700,500);
}
this.returnWords=function(){
return words[num];
}
this.return_y=function(){
return char_y;
}
this.returnTOP=function(){
char_y=50;
//newChar.style.display="none";
initChar();
}
this.speed=function(){
down++;
}
}
function CreateScoreBoard(){
var canvas;
var context;
var scores=0;
function initScoreBoard(){
//alert("coming initScoreBoard()");
canvas=document.getElementById("myCanvas");
//alert("canvas--"+canvas);
context=canvas.getContext("2d");
//alert("context--"+context);
context.font="20pt 黑体";
//context.fillText("得分：0",400,100);
}
initScoreBoard();
this.showScore=function(){
//context.clearRect(0,0,700,500);
context.font="25pt 黑体";
//context.fillText("",500,30);
context.fillText("得分："+scores,500,30);
}
this.addScores=function(){
scores+=10;
}
this.clearScore=function(){
//alert("coming clearContext()");
return context.clearRect(0,0,700,500);
}
this.returnScore=function(){
return scores;
}
}
</script>
</head>
<body>
<canvas id="myCanvas" width="700" height="500" style="border:1px solid black"></canvas>
</body>
</html>