Focus App – Dynamic personal landing page for your browser

Last week I created this little minimalist app with vanilla JavaScript, having features such as current weather, to-do list, etc. It’s entirely open-source. Check its GitHub repository for more details.

From the project’s readme file:

Focus is an application that aims to help you better organize your day. It contains interesting features as well as astonishing background images and beautiful minimalist responsive design. It is built with vanilla JavaScript and its whole code weights less than 25kb!

Online demo:
Source code:

“GoToTop”: a (scroll to top elevator) styled component for React JS with TypeScript

I am sharing here a “GoToTop” React JS component that I created today. This component will render a button (shaped as an arrow) when the user scrolls down, past a certain point. When clicked, this button will execute a handleGoToTop() function that will smoothly scroll the screen back to the top.

This is a styled component, making it very portable. It also uses React hooks and TypeScript.

1. The “GoToTop” component

// src/components/GoToTop/index.tsx

import React, { useState, useEffect } from 'react';
import { Container } from './styles';

const GoToTop: React.FC = () => {
  const [scrolled, setScrolled] = useState(false);

  useEffect(() => {
    window.addEventListener('scroll',() => {
      const isTop = window.scrollY < 150;

      isTop !== true ? setScrolled(true) : setScrolled(false);
  }, []);

  function handleGoToTop() {
      top: 0,
      behavior: "smooth"
  return (
        { scrolled && <button id="goToTop" onClick={() => handleGoToTop()} title="Go to top"></button> }

export default GoToTop;

Read more ““GoToTop”: a (scroll to top elevator) styled component for React JS with TypeScript”

Getting Started with Styled Components in React JS and TypeScript

Among the several strategies aimed at increasing the productivity of a development team, the proper organization of the code related to the software being conceived undoubtedly occupies a preponderant place. Over the years, several methods and tools have been created for this purpose. It is important to know them, especially since they can very concretely result in a substantial saving of time, at least in terms of maintenance activities and bug fixing.

In this context, we’ll take a look at how to deploy styled components in a React JS project with TypeScript using the styled-components library. This technique allows components to contain their own styles. This “encapsulation” of styles also involves CSS in JS, using tagged template literals.

Youtube demo:

Github repository:

First step: generation of files and installation of project dependencies

Generate React project files with TypeScript

create-react-app styled-components-demo --template typescript

Read more “Getting Started with Styled Components in React JS and TypeScript”


One more Rocketseat challenge completed!โœ”๏ธ ๐ ๐จ๐Œ๐š๐ซ๐ค๐ž๐ญ๐ฉ๐ฅ๐š๐œ๐ž is an e-commerce app, built with #ReactNative, #TypeScript and applying techniques such as #TDD, async storage and context API.




Source code

Available on my github:

API security and CORS: a NodeJS implementation

NodeJS logo

What is CORS

By default, browsers will block certain requests if both the client and the server are not in the same origin. Cross-origin resource sharing (CORS) is a specification designed to allow restricted resources from a remote server in a given origin, to be requested by a client associated to a different origin. An origin, as defined by the RFC6454, implies “identical schemes, hosts and ports”.

Usually the request from the browser will be accompanied by its corresponding HTTP headers, including the request’s origin. Example of the HTTP headers on the request:

Host: localhost:3000
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:77.0) Gecko/20100101 Firefox/77.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://localhost:3001/
Origin: http://localhost:3001
Connection: keep-alive
Cache-Control: max-age=0
If-None-Match: W/”10-iv0euXUvX8F10Ha2yy45d6DFMcI”

How does CORS work?

When CORS is not enabled, the response will not contain the Access-Control-Allow-Origin header and the browser will likely block it, as illustrated by the diagram below.

You will notice that although both the API and the client are in the same domain, the different HTTP ports result in both having different origins.
Read more “API security and CORS: a NodeJS implementation”

Quick user authentication and CRUD in Symfony 5

We will leverage on Symfony’s generators to quickly code a simple user authentication and CRUD system in less than 15 minutes.

Let’s start by creating a new Symfony project, which we will call sym_auth.

symfony new --full sym_auth

Then we will edit the .env file in the root folder, adding our database credentials.


Read more “Quick user authentication and CRUD in Symfony 5”

Symfony 5 – Select (or check box) for user roles in a form

For choosing between a html select or checkboxes on your form, just toggle the “multiple” parameter on the ChoiceType class. Since the roles are an array, we need a data transformer.



namespace App\Form;

use App\Entity\User;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
use Symfony\Component\Form\CallbackTransformer;

class UserType extends AbstractType
    public function buildForm(FormBuilderInterface $builder, array $options)
            ->add('Roles', ChoiceType::class, [
                    'required' => true,
                    'multiple' => false,
                    'expanded' => false,
                    'choices'  => [
                      'User' => 'ROLE_USER',
                      'Partner' => 'ROLE_PARTNER',
                      'Admin' => 'ROLE_ADMIN',



        // Data transformer
            ->addModelTransformer(new CallbackTransformer(
                function ($rolesArray) {
                     // transform the array to a string
                     return count($rolesArray)? $rolesArray[0]: null;
                function ($rolesString) {
                     // transform the string back to an array
                     return [$rolesString];


    public function configureOptions(OptionsResolver $resolver)
            'data_class' => User::class,

Set a bootstrap menu item as “active” in Symfony 5

In order to define a bootstrap menu item as “active” in a Symfony 5 project, you can add

{% set route_name = app.request.attributes.get('_route') %}

to the top of your base.html.twig. Then a twig condition in the navbar can be implemented as follows:

<li {% if route_name == "user_index" %} class="nav-item active" {% else %} class="nav-item" {% endif %} >

Read more “Set a bootstrap menu item as “active” in Symfony 5″