JS Rainbow Text Generator V2

<script>
var timer=0;
function toSpan(span) {
var str=span.firstChild.data;
var n=str.length;
span.removeChild(span.firstChild);
for(var i=0; i<n; i++) {
var theSpan=document.createElement("span");
theSpan.appendChild(document.createTextNode(str.charAt(i)));
span.appendChild(theSpan);
}
}
function RainbowSpan(span, hue, deg, brt, spd, hspd) {
this.deg=(deg==0?360:Math.abs(deg));
this.hue=(hue==0?0:Math.abs(hue)%360);
this.hspd=(hspd==0?3:Math.abs(hspd)%360);
this.length=span.firstChild.data.length;
this.span=span;
this.Div=(this.deg/this.length);
this.brt=(brt==0?255:Math.floor(brt)%256);
this.timer=0;
toSpan(span);
this.moveRainbow();
}
RainbowSpan.prototype.moveRainbow = function() {
if(this.hue>359) this.hue-=360;
var color;
var b=this.brt;
var n=this.length;
var h=this.hue;
for(var i=0; i<n; i++){
if(h>359) h-=360;
if(h<60){color=Math.round(((h)/60)*b);
red=b;
grn=color;
blu=0;
}
else if(h<120){ color=Math.round(((h-60)/60)*b);
red=b-color;grn=b;blu=0; }
else if(h<180){ color=Math.round(((h-120)/60)*b);
red=0;grn=b;blu=color; }
else if(h<240){ color=Math.round(((h-180)/60)*b);
red=0;grn=b-color;blu=b; }
else if(h<300){ color=Math.round(((h-240)/60)*b);
red=color;grn=0;blu=b; }
else{ color=Math.round(((h-300)/60)*b);
red=b;grn=0;blu=b-color; }
h+=this.Div;
this.span.childNodes[i].style.color="rgb("+red+", "+grn+", "+blu+")";
}
this.hue+=this.hspd;
}
</script>
<center>
<body bgcolor=black>
  <font color='red'>
<center>Enter Text To Make Rainbow:<br><input type="input" size="50" id="rainbowtext" onclick="rainbowtext.value=('');"><br><br>
<tr><td colspan="2" align="center"><input type="button" value='Generate Rainbow Text Now!!' onClick="rainbow();"><div style="font-size: 12px;color: #dadada;" id="dumdiv">
</div>
<br>
<tr><td align='center' colspan='2'>
<div id="r1"></div>
</td></tr></table>
</form>
<script type="text/javascript">
function rainbow(){
var text=document.getElementById("rainbowtext").value;
document.getElementById("r1").innerHTML=text;
var r1=document.getElementById("r1");
var myRainbowSpan=new RainbowSpan(r1, 0, 316, 215, 30, 15);
}
</script>