function validateLink(url) {
  var BAD_PROTOCOLS = [ 'vbscript', 'javascript', 'file', 'data' ];
  var str = url.trim().toLowerCase();
  // Care about digital entities "javascript&#x3A;alert(1)"
  str = utils.replaceEntities(str);
  if (str.indexOf(':') !== -1 && BAD_PROTOCOLS.indexOf(str.split(':')[0]) !== -1) {
    return false;
  }
  return true;
}
Validate the given `url` by checking for bad protocols.

@param  {String} `url`
@return {Boolean}