Dán code bên duwois vào HTML/Javarscip nha.
Demo ngay tại bài viết này:
<style type='text/css'>
body {background: #ff449d url(https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPxLn8GJ_da_DngPx2oqUYKqHbK-h90Hq9B9mXw6FUOFySTVNJHyYNTnNueQX3OGZNGvcI-wXlaTmmie-pp5zDm_QM-p74egIbZqHYhH2-m0cAqlYhtrB7GlduQmp00PYNyYsHckCebRU/s1600/buom-namkna-blogspot-com.gif) repeat scroll top left;
}
</style>
<script type='text/javascript'>//<![CDATA[
var fallObjects=new Array();function newObject(url,height,width){fallObjects[fallObjects.length]=new Array(url,height,width);}
///////////// Thông số //////////////
var numObjs=20, waft=50, fallSpeed=10, wind=0;
newObject("https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhy3fqQ6dIBW1kxY9qH_jBgb_tKIzLcXwp1BC7jb3xLeeKbiWMerk9p4Jc40ZGzoc6iXO37UWR2zZeFoHM7UgT8h267DOkZ89PZHQcczSIP-iNcQlodUkLYHyrMgBa9Z4R0gfyDycgMaqA/s1600/heart-namkna-blogspot-com.gif",16,15);
newObject("https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhy3fqQ6dIBW1kxY9qH_jBgb_tKIzLcXwp1BC7jb3xLeeKbiWMerk9p4Jc40ZGzoc6iXO37UWR2zZeFoHM7UgT8h267DOkZ89PZHQcczSIP-iNcQlodUkLYHyrMgBa9Z4R0gfyDycgMaqA/s1600/heart-namkna-blogspot-com.gif",16,15);
//////////////////////////////////////////////
function winSize(){winWidth=(moz)?window.innerWidth-180:document.body.clientWidth-180;winHeight=(moz)?window.innerHeight+500:document.body.clientHeight+500;}
function winOfy(){winOffset=(moz)?window.pageYOffset:document.body.scrollTop;}
function fallObject(num,vari,nu){
objects[num]=new Array(parseInt(Math.random()*(winWidth-waft)),-30,(parseInt(Math.random()*waft))*((Math.random()>0.5)?1:-1),0.02+Math.random()/20,0,1+parseInt(Math.random()*fallSpeed),vari,fallObjects[vari][1],fallObjects[vari][2]);
if(nu==1){document.write('<img id="fO'+i+'" style="position:fixed;" src="'+fallObjects[vari][0]+'">'); }
}
function fall(){
for(i=0;i<numObjs;i++){
var fallingObject=document.getElementById('fO'+i);
if((objects[i][1]>(winHeight-(objects[i][5]+objects[i][7])))||(objects[i][0]>(winWidth-(objects[i][2]+objects[i][8])))){fallObject(i,objects[i][6],0);}
objects[i][0]+=wind;objects[i][1]+=objects[i][5];objects[i][4]+=objects[i][3];
with(fallingObject.style){ top=objects[i][1]+winOffset+'px';left=objects[i][0]+(objects[i][2]*Math.cos(objects[i][4]))+'px';}
}
setTimeout("fall()",31);
}
var objects=new Array(),winOffset=0,winHeight,winWidth,togvis,moz=(document.getElementById&&!document.all)?1:0;winSize();
for (i=0;i<numObjs;i++){fallObject(i,parseInt(Math.random()*fallObjects.length),1);}
fall();
//]]></script>
