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Let’s talk about another common coding challenge using JavaScript.

This is not just common, but a very tricky exercise to solve. At first, it seems simple and with the right approach, we can make it a win.

The instructions to complete are the following:


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Most people looking into a Software Engineer role will likely face a technical interview and probably a coding challenge. One of the common questions is the Reverse Integer.


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Writing JavaScript code can be intimidating at first, then difficult when you dig in, but then with the right approach, it can be quite fun and rewarding. Being one of the most important and popular programming languages it became a powerful tool to learn and is incredibly effective for frontend and backend development.

An essential topic to understand is arrays, which is the data type that we are going to learn methods for today. The official documentation defines an array in these words: “Arrays are list-like objects whose prototype has methods to perform traversal and mutation operations. Neither the length…


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When we talk about types in programming languages the first thoughts that come to our minds are strings, boolean, number, etc. Which is a general concept that can be called “Data Types”. Here I would like to briefly expose some basic concepts of Javascript that can easily get unnoticed and as a result, create bugs in any application.

In Javascript, there are two categories which are Primitive and Reference Types. For instance, Primitive are those represented directly at the lowest level of the language implementation. Another truth about primitive types is that they are immutable, it is important not to…


The second part of the project will be dedicated to explore updates and delete.

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In Part I of the article, we covered some important aspects of interacting with APIs. We learned the importance of understanding the documentation before start coding, the use of tools like Postman, to help us interact with APIs and the fetch function using the GET and POST method.

For the second phase of our Contact List, the topics to be explored are PUT that allows us to update the current data (the contact) and DELETE that is very intuitive the results we can get from this last method.

The first step is checking the documentation for update data. …


Another interesting project to explore React features and their interactions with APIs.

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In the previous article, we learned how to fetch data from a third-party API and return this data to the application. You can check the previous project here.

This time we will build a contact list application using React and explore features to create, update and delete items. These interactions are very common on a software developer’s daily basis.

Before start diving and coding our app, I want to show you how is going to be at the end:

https://youtu.be/ho-yWvLUjPU

For every opportunity of interacting with external data, there will be different steps to follow, therefore reading and understanding its…


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Using the boilerplate provided by 4Geeks Academy on Github (which I recommend for starting a new react application) we are going to explore how to use the fetch() method in a react application.

In this article, I will explore how to access a public API which will be the Star Wars API and retrieve its data by using the GET method.

We are going to access 3 different endpoints:

https://swapi.co/api/planets, https://swapi.co/api/people, and https://swapi.co/api/vehicles (*exclude the commas*).

Using Postman we can access the data we are going to fetch and make sure the endpoint is correct. …


SSL Certificates

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Also known as SSL/TSL certificate, Digital Certificate, Public Key Certificate triggers the “little padlock” or green bar in the browser. It uses HTTPS for secure communication and certifies the ownership of a public key. The SSL is used for encrypting data sent between the browser and a remote server.

SSL stands for Secure Socket Layer, a cryptographic protocol for communication security. While TLS stands for Transport Layer Security.

A certificate content :
- Organization
- URL
-State, Country
-Valid date range
-Issuer
Its purpose is encryption, Identity, and trustworthiness.

Handshake and Cryptography: Symmetric-key Cryptography - Let’s you encrypt…

João Henrique Xavier

Software Developer

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