url-helpers

/* Detects ftp | ftps | http | https and prepends http:// if none */
function ensureUrlScheme(url) {
   if (!/^(((f|ht)tps?)|chrome-extension):\/\//i.test(url)) {
      url = "http://" + url;
   }
   return url;
}

/* Detects the scheme of the url, removes it */
function detachUrlScheme(url) {
  if (url.indexOf('https://') > -1) {
    return url.replace('https://', '');
  } else if (url.indexOf('http://') > -1) {
    return url.replace('http://', '');
  } else {
    return null;
  }
}

/* Ensure URL is valid */
function isUrlValid(str) {
  var pattern = new RegExp('^((https?:\\/\\/)?'+ // protocol
  '((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|'+ // domain name
  '((\\d{1,3}\\.){3}\\d{1,3}))'+ // OR ip (v4) address
  '(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*'+ // port and path
  '(\\?[;&a-z\\d%_.~+=-]*)?'+ // query string
  '(\\#[-a-z\\d_]*)?)|(chrome-extension://.*)$','i'); // fragment locator
  if(!pattern.test(str)) {
    return false;
  } else {
    return true;
  }
}