text: const formLogin = elemento( "#form-login" );
  
  const isUser = ( inputUser ) => {
    if ( typeof inputUser == "undefined" || inputUser === null )
      return false;
  
    let pattern = /^[a-z]{1}[a-z\-\_\.]{4,16}[a-zA-Z0-9]{1}$/i;
    return pattern.test( inputUser.value.trim() );
  }
  
  const isPassword = ( inputPassword ) => {
    if ( typeof inputPassword == "undefined" || inputPassword === null )
      return;
      
    let pattern = /^[a-z0-9\-\_\.\*\%\&\/\\\Ñ\ñ\$\#\@\|\!\[\]\+\¿\?\(\)\¬\{\}]{8,30}$/i;
    return pattern.test( inputPassword.value.trim() );
  }
  
  // Detectar envío de formulario:
  if ( formLogin !== null )
    formLogin.onsubmit = e => {
      let user = elemento( "#user" ),
        pass = elemento( "#password" );
  
      if ( user === null || pass === null )
        e.preventDefault();
  
      if ( ! isUser( user ) ) {
        e.preventDefault();
        user.classList.add( "loginAnimation");
  
        user.onanimationend = () => {
          user.classList.remove( "loginAnimation" );
        }
      }
  
      if ( ! isPassword( pass ) ) {
        e.preventDefault();
        pass.classList.add( "loginAnimation");
  
        pass.onanimationend = () => {
          pass.classList.remove( "loginAnimation" );
        }
      }
    };
  
  