Javascript – Validate URL function

Function:

function checkUrl(theUrl){
if(theUrl.indexOf(“http://”)!=-1 || theUrl.indexOf(“https://”)!=-1 || theUrl.indexOf(“www.”)!=-1){
return true;
} else {
alert(“Wrong address.”);
return false;
}
}

Function call:

var url = “http://google.com/”;
alert(checkUrl(url));