JavaScript实现躲避下落纸片的简易小游戏

HTML与CSS样式结构

<!DOCTYPE html>

<html>

<head>

<style>
 .move
 {
  margin-top: 0px;
  width:40px;
  height: 50px;
  background: #ff0;
  position:absolute;
  z-index: 999;
 }


 .self
 {
  width:40px;
  height: 50px;
  background: #f0f;
  position:absolute;
  margin-top: 600px;
  margin-left: 643px;
  z-index: 999;
 }

 .self img
 {
  width:40px;
  height: 50px;
  border-radius: 20px;
 }

</style>

<title>图图up up</title> 

</head>

<body onload="moveDiv()">
 <!--12个div就是空中的小纸片-->
 <div class="move" style="margin-left:100px">

 </div>

 <div class="move" style="margin-left:200px">

 </div>
 <div class="move" style="margin-left:300px">

 </div>
 <div class="move" style="margin-left:400px">

 </div>

 <div class="move" style="margin-left:500px">

 </div>
 <div class="move" style="margin-left:600px">

 </div>
 <div class="move" style="margin-left:700px">

 </div>
 <div class="move" style="margin-left:800px">

 </div>

 <div class="move" style="margin-left:900px">

 </div>
 <div class="move" style="margin-left:1000px">

 </div>
 <div class="move" style="margin-left:1100px">

 </div>
 <div class="move" style="margin-left:1200px">

 </div>

 <!--小人儿用一张图片代替-->
 <div id="self" class="self">
  <img src="images/tutu.jpg">
 </div>

</body>

<script type="text/javascript">

 var alldiv = document.querySelectorAll('.move');
 var selfdiv = document.getElementById("self");
 var timer, flag;
 function moveItem()
 {
  //用随机数决定哪一张纸片掉落
  for (var j = 0; j < Math.round(Math.random()*11); j++) 
  {

   var i = Math.round(Math.random()*11);
   alldiv[i].style.top = alldiv[i].offsetTop + 20 +"px";

   //掉落过程中改变纸片的颜色
   var rgb='rgb('+Math.floor(Math.random()*255)+','
      +Math.floor(Math.random()*255)+','
      +Math.floor(Math.random()*255)+')';
   alldiv[i].style.backgroundColor = rgb;

   if (alldiv[i].offsetTop >= 600)
   {
    alldiv[i].style.top = "50px"; //当纸片落到底部，又重新回到起点
   }
  }

 }

 function moveDiv()
 {
  timer = setInterval(moveItem,20); //每隔20ms掉落
  flag = setInterval(meeting,1); //间隔1ms判断是否相撞
 }

 var selfdiv = document.getElementById("self");
 selfdiv.onmousedown = function(e) //鼠标点击小人儿开始移动
 {
  document.onmousemove = function(e) //小人儿跟着鼠标移动
  {
   if (e.clientY > 600)
   {
    selfdiv.style.marginTop = "600px"; //如果到达屏幕底部就不再往下
   }
   else if(e.clientX > 1300)
   {
    selfdiv.style.marginLeft = "1300px"; //到达最右部就回到不再往右
   }
   else
   {
    //小人儿的位置始终等于鼠标的位置
    selfdiv.style.marginTop = e.clientY + "px";
    selfdiv.style.marginLeft = e.clientX + "px";
   }
  }
 }

 function meeting()
 {
  for (var i = 0; i < alldiv.length; i++)
  {
   //判断是否相撞
   if (Math.abs(alldiv[i].offsetTop-selfdiv.offsetTop) <= 50 && 
    Math.abs(alldiv[i].offsetLeft-selfdiv.offsetLeft) <= 40)
   {
    clearInterval(flag);
    clearInterval(timer);
    alert("一不小心撞到了！！！游戏结束");
   }
  }
 }

</script>

</html>