Animate SnowFall in your webpage with CSS and JavaScript

In this post, we are going to learn to animate a snowfall in webpage using CSS and JavaScript.

The full source code for this animation is as follows :

 

<script>
var snowmax=75;
var snowcolor=new Array("#4285f4","#cc181e","#008000");
var snowtype=new Array("Arial Black","Arial Narrow","Times","Comic Sans MS");
var snowletter="*";
var sinkspeed=0.6;
var snowmaxsize=50;
var snowminsize=18;
var snowingzone=3;



var snow=new Array();
var marginbottom;
var marginright;
var timer;
var i_snow=0;
var x_mv=new Array();
var crds=new Array();
var lftrght=new Array();
var browserinfos=navigator.userAgent;
var ie5=document.all&&document.getElementById&&!browserinfos.match(/Opera/);
var ns6=document.getElementById&&!document.all;
var opera=browserinfos.match(/Opera/);
var browserok=ie5||ns6||opera;

function randommaker(range) {		
  rand=Math.floor(range*Math.random());
    return rand;
}

function initsnow() {
  if (ie5 || opera) {
    marginbottom = document.body.clientHeight;
    marginright = document.body.clientWidth;
  }
  else if (ns6) {
    marginbottom = window.innerHeight;
    marginright = window.innerWidth;
  }
  var snowsizerange=snowmaxsize-snowminsize;
  for (i=0;i<=snowmax;i++) {
    crds[i] = 0;                      
    	lftrght[i] = Math.random()*15;         
    	x_mv[i] = 0.03 + Math.random()/10;
    snow[i]=document.getElementById("s"+i);
    snow[i].style.fontFamily=snowtype[randommaker(snowtype.length)];
    snow[i].size=randommaker(snowsizerange)+snowminsize;
    snow[i].style.fontSize=snow[i].size;
    snow[i].style.color=snowcolor[randommaker(snowcolor.length)];
    snow[i].sink=sinkspeed*snow[i].size/5;
    if (snowingzone==1) {snow[i].posx=randommaker(marginright-snow[i].size)}
    if (snowingzone==2) {snow[i].posx=randommaker(marginright/2-snow[i].size)}
    if (snowingzone==3) {snow[i].posx=randommaker(marginright/2-snow[i].size)+marginright/4}
    if (snowingzone==4) {snow[i].posx=randommaker(marginright/2-snow[i].size)+marginright/2}
    snow[i].posy=randommaker(2*marginbottom-marginbottom-2*snow[i].size);
    snow[i].style.left=snow[i].posx;
    snow[i].style.top=snow[i].posy;
  }
  movesnow();
}

function movesnow() {
  for (i=0;i<=snowmax;i++) {
    crds[i] += x_mv[i];
    snow[i].posy+=snow[i].sink;
    snow[i].style.left=snow[i].posx+lftrght[i]*Math.sin(crds[i]);
    snow[i].style.top=snow[i].posy;
    
    if (snow[i].posy>=marginbottom-2*snow[i].size || parseInt(snow[i].style.left)>(marginright-3*lftrght[i])){
      if (snowingzone==1) {snow[i].posx=randommaker(marginright-snow[i].size)}
      if (snowingzone==2) {snow[i].posx=randommaker(marginright/2-snow[i].size)}
      if (snowingzone==3) {snow[i].posx=randommaker(marginright/2-snow[i].size)+marginright/4}
      if (snowingzone==4) {snow[i].posx=randommaker(marginright/2-snow[i].size)+marginright/2}
      snow[i].posy=0;
    }
  }
  var timer=setTimeout("movesnow()",50);
}

for (i=0;i<=snowmax;i++) {
  document.write("<span id='s"+i+"' style='position:absolute;top:-"+snowmaxsize+"'>"+snowletter+"</span>");
}
if (browserok) {
  window.onload=initsnow;
}
</script>