JavaScript生成的动态下雨背景效果实现方法_javascript技巧

for(i=0; i initRain();
if (i == 0) {
document.write(" document.write("absolute; Z-INDEX: "+ i +"; VISIBILITY: ");
document.write("visible; TOP: 15px; LEFT: 15px;\">");
document.write(","); }
else {
document.write(" document.write("absolute; Z-INDEX: "+ i +"; VISIBILITY: ");
document.write("visible; TOP: 15px; LEFT: 15px;\">");
document.write(",."); }
}

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();

希望本文所述对大家的javascript程序设计有所帮助。