Javascript下雪功能？

Question

這就是我在做的功能，我唯一想改變的就是雪中出現的一切;所以它不在divs之上。我只是想讓它出現在一切的背景中。這是代碼。

<script type="text/javascript"> 
    // Set the number of snowflakes (more than 30 - 40 not recommended) 
    var snowmax=35 

    // Set the colors for the snow. Add as many colors as you like 
    var snowcolor=new Array("#aaaacc","#ddddff","#ccccdd","#f3f3f3","#f0ffff") 

    // Set the fonts, that create the snowflakes. Add as many fonts as you like 
    var snowtype=new Array("Times","Arial","Times","Verdana") 

    // Set the letter that creates your snowflake (recommended: *) 
    var snowletter="*" 

    // Set the speed of sinking (recommended values range from 0.3 to 2) 
    var sinkspeed=0.6 

    // Set the maximum-size of your snowflakes 
    var snowmaxsize=30 

    // Set the minimal-size of your snowflakes 
    var snowminsize=8 

    // Set the snowing-zone 
    // Set 1 for all-over-snowing, set 2 for left-side-snowing 
    // Set 3 for center-snowing, set 4 for right-side-snowing 
    var snowingzone=1 

    /////////////////////////////////////////////////////////////////////////// 
    // CONFIGURATION ENDS HERE 
    /////////////////////////////////////////////////////////////////////////// 


    // Do not edit below this line 
    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.scrollHeight 
        marginright = document.body.clientWidth-15 
      } 
      else if (ns6) { 
        marginbottom = document.body.scrollHeight 
        marginright = window.innerWidth-15 
      } 
      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+'px'; 
        snow[i].style.color=snowcolor[randommaker(snowcolor.length)] 
        snow[i].style.zIndex=1000 
        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+'px'; 
        snow[i].style.top=snow[i].posy+'px'; 
      } 
      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])+'px'; 
        snow[i].style.top=snow[i].posy+'px'; 

        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> 

Answer 1

變化

snow[i].style.zIndex=1000 

它設置爲

snow[i].style.zIndex=-1;