Generate color rainbow list items

colorrainbow.js

function getColor(noOfColors){
    		html="";
    		frequency=5/noOfColors;
			for (var i = 0; i < noOfColors; ++i){
                
                var xspan=(i%10)+2;
                var yspan=Math.floor(i/10);
                yspan=(1-yspan/2);

                r =   Math.sin(frequency*i + 0) * (127) + 128;
                g =   Math.sin(frequency*i + 2) * (127) + 128;
                b =   Math.sin(frequency*i + 4) * (127) + 128;
                
			    li='<li class="color" style="background-color:rgb({r},{g},{b});">  </li>';
			    li=li.replace("{r}",Math.floor(r));
			    li=li.replace("{g}",Math.floor(g));
			    li=li.replace("{b}",Math.floor(b));
			    html=html+li;
			}
			return html; 
    	}