function replace(s,oldstr,newstr) 
{ 
olen=oldstr.length;
if(olen<1) return s;
var news="";
var i; 
s2=s;
i=s2.indexOf(oldstr)
while(i>0) 
{
news+=s2.substring(0, i)+newstr;
s2=s2.substring(i+olen,s2.length); 
i=s2.indexOf(oldstr); 
} 
news+=s2;
return news; 
}