JavaScript实现随机星星背景特效代码详解

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<script type="text/javascript">
//定义全局变量
var img_width_min = 15;
var img_width_max = 80;
var x_left = 0;
var x_right = 0;
var y_top = 0;
var y_bottom = 0;

//定义初始化的函数
function init()
{
 document.body.bgColor = "#000";
 x_right = window.innerWidth - img_width_max;
 y_bottom = window.innerHeight - img_width_max;
 //定时器
 setInterval("showStar()",1000);
}
//显示星星
function showStar()
{
 //创建一个图片
 var node_img = document.createElement("img");
 //随机图片大小和随机坐标
 var width = getRandom(img_width_min,img_width_max);
 var x = getRandom(x_left,x_right);
 var y = getRandom(y_top,y_bottom);
 //增加src的属性
 node_img.setAttribute("src","images/xingxing.gif");
 //增加style属性
 var style = "position:absolute;left:"+x+"px;top:"+y+"px;";
 style += "width:"+width+"px;";
 node_img.setAttribute("style",style);
 //增加一个onclick事件属性
 node_img.setAttribute("onclick","removeImg(this)");
 //将图片追加到<body>元素下
 document.body.appendChild(node_img);
}
function removeImg(obj)
{
 document.body.removeChild(obj);
}
function getRandom(min,max)
{
 return Math.floor(Math.random()*(max-min)+min);
}
</script>
</head>

<body onload="init()">
</body>
</html>