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JavaScript生成的动态下雨背景效果实现方法

代码家园 人气:0

本文实例讲述了JavaScript生成的动态下雨背景效果实现方法。分享给大家供大家参考。具体实现方法如下:

复制代码 代码如下:
<HTML>
<HEAD>
<TITLE>JavaScript生成的动态下雨背景效果</TITLE>
</HEAD>
<BODY bgcolor="#fef4d2" >
<center>
<script language=JavaScript>
<!-- [Step1]: 在此能够设置雨滴的多少 -->
var rainsize = 40;
<!-- [Step2]: 这里可以更改下雨的速度,数值大速度慢 -->
var speed = 10;
var x = new Array();
var y = new Array();
var r = new Array();
var cx = new Array();
var cy = new Array();
var doc_width = document.body.clientWidth;
var doc_height = document.body.clientHeight;

for(i=0; i<rainsize; ++i) {
  initRain();
  if (i == 0) {
    document.write("<div id=\"dot"+ i +"\" style=\"POSITION: ");
    document.write("absolute; Z-INDEX: "+ i +"; VISIBILITY: ");
    document.write("visible; TOP: 15px; LEFT: 15px;\"><font color=\"blue\">");
    document.write(",</font></div>"); }
  else {
    document.write("<div id=\"dot"+ i +"\" style=\"POSITION: ");
    document.write("absolute; Z-INDEX: "+ i +"; VISIBILITY: ");
    document.write("visible; TOP: 15px; LEFT: 15px;\"><font color=\"blue\">");
    document.write(",.</font></div>");  }
}

function initRain() {
  a = 6;
  r[i] = 1;
  sn = Math.sin(a);
  cs = Math.cos(a);
  cx[i] = Math.random() * doc_width + 1;
  cy[i] = Math.random() * doc_height + 1;
  x[i] = r[i] * sn + cx[i];
  y[i] = cy[i];
}

function raindropIE() {
  for (i = 0; i < rainsize; ++ i) {
     updateRain();
     if ((x[i] <= 1) || (x[i] >= (doc_width - 20)) || (y[i] >= (doc_height - 20))) {
         makeRain();
         doc_width = document.body.clientWidth;
         doc_height = document.body.clientHeight; }
     document.all["dot"+i].style.pixelTop = y[i];
     document.all["dot"+i].style.pixelLeft = x[i]; }
  setTimeout("raindropIE()", speed);
}
function updateRain() {
  r[i] += 10;
  x[i] = r[i] * sn + cx[i];
  y[i] = r[i] * cs + cy[i];
}
function makeRain() {
  r[i] = 1;
  cx[i] = Math.random() * doc_width + 1;
  cy[i] = 1;
  x[i] = r[i] * sn + cx[i];
  y[i] = r[i] * cs + cy[i];
}
raindropIE();
</script>
</BODY>
</HTML>

希望本文所述对大家的javascript程序设计有所帮助。

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