function url_validator(txt_url) {
/*if(txt_url.value==""){
alert("please enter web url");
txt_url.focus();
return false ;
}*/
x1=(txt_url.value.substring(0,txt_url.value.indexOf(":")) == "ftp");
x2=(txt_url.value.substring(0,txt_url.value.indexOf(":")) == "http");
x3=(txt_url.value.substring(0,txt_url.value.indexOf(":")) == "https");
//url www. checking it should not be like http://www. only
// txt_url.value.substring(indexOf(":")+1,indexOf(":")+3) == "\\\\"||"//"
y1=(txt_url.value.substring(txt_url.value.indexOf(":")+1,txt_url.value.indexOf(":")+3) == "\\\\");
y2=(txt_url.value.substring(txt_url.value.indexOf(":")+1,txt_url.value.indexOf(":")+3) == '//');
//check www.xyz  need second .
if(txt_url.value.indexOf("www.")>=0)
{
str2=txt_url.value.substring(txt_url.value.indexOf("www")+4);
if(str2.indexOf(".")>=0)
z3=true;
else
z3=false;
}
else
{
	z3=true;
	}
//check wwww.
//document.write(str.lastIndexOf("."))
if(txt_url.value.lastIndexOf(".")!=txt_url.value.length-1){
	z1=true;
}
	else{
	z1=false;
}
//document.write()
z2=txt_url.value.indexOf(".")>0;
if((x1 || x2 || x3) && (y1 || y2) && z2 && z1 && z3){
return true;
}
else{
alert("Please enter correct web url");
txt_url.focus();
return false;
}
}