At the beginning of 2020, we decided to change our interview process for our frontend candidates by introducing a new frontend test that tries to take away the pressure of coding challenges.

It is time to say goodbye to the whiteboard interview

A little bit about LumApps

What was our frontend interview process like before?


For the last couple of years we have been slowly transitioning our application frontend application from Angular JS v1 to React JS while adding several performance enhancements to the our application. In the last couple of months we managed to put into production our first fully React JS frontend page (with the help of our new monorepo architecture)and we wanted to share how we did it and the results that we have obtained!

The sun is setting on our Angular JS application and the road to fully React is now more clearer than ever!

A little bit about LumApps


This is an actual picture of our development envirnoment after we created a mock server for our repo

With an increasing amount of services being created on our backend, our frontend development started to be impacted by how many repos and servers you needed to install locally to get the frontend going. And if we also take into consideration our frontend architecture rework, we knew we had to take action in order to have a fast and smooth development experience. That is where our monorepo mock server comes in.


Up until last year, at LumApps we were struggling to kick start our migration of our frontend application from Angular JS to React. Fortunately, a superhero called Monorepo came to the rescue and helped things take off!

A little bit about LumApps

Where we were up until last year


PR reviews are such a huge central part of our daily routines that how you actually approach them can have an impact on the other developers

Actual picture of you looking at your PR before it is reviewed

Pull request review is a really popular mechanism that we have today that allows engineers to validate a set of changes that will be applied to the source code, in order to have a verification step before merging them. It is a great step to check for code legibility and maintainability, as well as validating that our code is doing what we expect it to do, and that we are taking into consideration the different variables that could affect that code.

That is as far as code is concerned, but what about the people involved in that PR 🤔? How…


Quick example on how a refactor to your components can make your life so much easier!

I have been working with React over a couple of years now, and over those years, I have noticed that there is a development life cycle ♻️ that tends to repeat itself for each component. We create a simple component on a single file, with no more than 30 - 40 lines of code where you define how it works, its internal state and how it is rendered to the end user. You also create a test file, where you test the logic that you implemented, passing different props and seeing how your component behaves.

Up until now, everything looks…


On May 26, we held a React JS workshop in Mercado Libre!

In recent years, in Mercado Libre, we have begun to use new technologies in all our frontends. It has been a long way, but now we have a Frontend technological Stack that has the following components:

  • Node JS as the server for our frontend applications
  • React JS for our client-side code
  • Webpack

With this new adoption, it has really been a change in our way of working and developing. We have substantially lowered the development, generation of versions and deployment times, as well as installation and testing times. …


Rendering search filters in eCommerce websites have always been a real tricky subject, and the Color filter is no exception!

Implementing this guy can get real tricky real fast!

Search filters are one of the most important aspects of eCommerce websites, allowing our customers to refine their results and find what they are really looking for. In order to do that, we usually try to make these filters as useful and usable as possible, since we want them to be really helpful and provide a great experience for our customers. From a frontend technical perspective, the filters design can turn into a complex problem to resolve, which can impact both usability, maintainability and performance of our search result pages.

Our contestants


Have you ever wondered how exceptions start to shape and have an impact on your project? Are they useful? Do they affect performance in anyway?

Sometimes exceptions can be thrown from the smallest operations!

During a recent class at my University there was a specific discussion related to exceptions and how they can take a toll on your project. Most of the conversation involved arguments about how exceptions work, when are they useful and how they affect your project, from several perspectives; code readability, coupling, performance and overall usefulness of exceptions. I wanted to explore this idea a little bit and see what implications exceptions have when you start using them.

In my experience, exception handling is a very vast and discussed topic, with several different opinions on it, which usually are formed due…

Juani Galán

Frontend Software Engineer @Lumapps working with React. Former @mercadolibre @oracle. I love creating the best web experiences for developers and end Users!

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