Juan Elfers

5.0

(2120 reviews)

US$25.00

For every 15 mins

4371

Sessions/Jobs

ABOUT ME

Sr. Full-stack Developer

JavaScript, ReactJS, NodeJS, HTML+CSS... and much more!

With more than a decade developing software (and more than 5 years at Codementor!) I always advocate for the best available solutions and the cleanest code. I also love to explain how and why things works so you can also learn more from it.

These are some of the things I can help you with:

ReactJS / NextJS
Vercel / Remix / Supabase
NodeJS / Express
JavaScript / Typescript
Databases (SQL, Postgres, Mongo, Firestore, ...)
Angular
Puppeteer (NodeJS)
HTML + CSS/Sass
Git, npm
UX / UI
PHP

Spanish, English

Buenos Aires (-03:00)

Joined July 2018

EXPERTISE

React

7 years experience | 295 endorsements

You've been trying to learn React but you still don't fully get it? You're not sure how hooks work, when to use them, or how the custom h...

You've been trying to learn React but you still don't fully get it? You're not sure how hooks work, when to use them, or how the custom hook you have is working? Confused about class components vs function components? useEffect, react-router, or functions like .map and .filter still don't make much sense to you? If that's the case, or if you have something in React you need to fix or implement, drop me a message, I'll have the answer

Node.js

5 years experience | 64 endorsements

Node is the present and future of web servers. It is not only used for serving files and database manipulation, but also for frontend eve...

Node is the present and future of web servers. It is not only used for serving files and database manipulation, but also for frontend everyday development, and that's one of the reasons why Node is so important for the web.

Express.jsNode.js express.jsPuppeteer

Express.jsNode.js express.jsPuppeteer Electron.js Socket.IO

JavaScript

10 years experience | 670 endorsements

Javascript is my main language. I've been using it since I started programming and I use it every day for building websites, apps and se...

Javascript is my main language. I've been using it since I started programming and I use it every day for building websites, apps and servers. I've used several libraries and frameworks and I know the latest features of the language. If you need someone who knows Javascript, count on me!

Es6 GSAP npm

Es6 GSAP npm JavaScript OOP CoffeeScript Handlebars.js AJAX

Solidjs

1 year experience | 8 endorsements

The syntax is very similar to ReacJS; it actually uses JSX. But the performance of SolidJS is outstanding and this is one of the reasons ...

The syntax is very similar to ReacJS; it actually uses JSX. But the performance of SolidJS is outstanding and this is one of the reasons you should be using it. Ping me if you need some help with Solid!

React JavaScript

HTML/CSS

13 years experience | 185 endorsements

I have been creating, editing, refactoring, fixing and maintaining websites for more than 10 years. I've used professionally almost any H...

I have been creating, editing, refactoring, fixing and maintaining websites for more than 10 years. I've used professionally almost any HTML feature, including the latest HTML5 tags and attributes. I use semantic, clean and organized HTML and I always choose the best possible way to create a document structure. If you need to learn HTML, CSS, or build a website, count on me; you'll see a great code quality on everything I do.

HTML5 CSS3Html/css, javascript, php

HTML5 CSS3Html/css, javascript, phpHTMLSass lessFull stack web developmentFull Stack

Angular

7 years experience | 24 endorsements

I've built a few Angular (+v2) and AngularJS (v1) apps and it is one of my favorite JS frameworks

Angular 2 Angular Material Design

CSS3

13 years experience | 235 endorsements

I know in depth all the CSS potential with it's media queries, flex and grid layout, animations, transitions and every thing that can be ...

I know in depth all the CSS potential with it's media queries, flex and grid layout, animations, transitions and every thing that can be styled and manipulated with this great language. I also use Sass/SCSS pre-processors everyday to be more time efficient and to improve code quality. Just let me know if you need some help with CSS.

Sass LESS

REVIEWS FROM CLIENTS

5.0

(2120 reviews)

Manuel Urbina

April 2024

Somehow my page went into an infinity loop and break, he was able to find my mistake and fix it! Thank you!

Bo Reahard

March 2024

Awesome as always

Manuel Urbina

March 2024

He was quick to help and to teach me more about CSS!

Manuel Urbina

March 2024

I told him I wanted to embed some code in Wordpress and he did it so effortlessly! Thank you so much!

Carina

March 2024

Juan was super helpful, recommended resources and helped me with my issue while explaining everything.

Erin Smith

February 2024

EXCELLENT! Juan does an excellent job explaining extra concepts to HTML, CSS, and JavaScript, while not making you feel dumb.

Erin Smith

February 2024

Very helpful and I've been working with Juan for 4 years.

Dan

January 2024

Highly recommend. Juan solves complicated problems with elegant solutions. I always feel fortunate to be able to work with him.

Michael

December 2023

Juan continues to amaze me with how he works. If you're stuck on a problem I recommended reaching out to him

Erin Smith

November 2023

Juan is very helpful with showing you how to solve problems and show many ways of understanding issues and not making you feel overwhelmed or dumb. It's rare but you need to work with him because it's money well spent!

SOCIAL PRESENCE

GitHub

collector-extension

JavaScript

some-coding

JavaScript

EMPLOYMENTS

Fullstack dev/mentor

Codementor

2018-10-01-Present

Freelancer and tutor @ Codementor
• Participated in an extensive range of jobs from frontend to backend.
• Tutored and helped ...

Freelancer and tutor @ Codementor
• Participated in an extensive range of jobs from frontend to backend.
• Tutored and helped plenty of programmers, mainly in Javascript, React, Node, jQuery and HTML/CSS
• Worked with and helped hundreds of programmers and programming students during the last 4 years
• Gained experience working on a very diversified kind of projects

HTML/CSS

PHP

Python

HTML/CSS

PHP

Python

Node.js

Angular

Firebase

React

JavaScript

Redux

Frontend Developer

Fizzmod

2016-02-01-2018-09-01

At Fizzmod I developed high-traffic e-commerce websites over the Vtex platform. Worked with Product to develop unique experiences inte...

At Fizzmod I developed high-traffic e-commerce websites over the Vtex platform. Worked with Product to develop unique experiences integrating disparate sources of data into a seamless experience. Additionally built multiple desktop applications with ElectronJS for optimized applications.

HTML/CSS

Angular

React

HTML/CSS

Angular

React

JavaScript

Electron

Fullstack Developer

Freelancer

2010-01-01-2016-01-01

During my first years as a developer, I worked with PHP and MySQL building CRUD systems for small businesses. I also developed several...

During my first years as a developer, I worked with PHP and MySQL building CRUD systems for small businesses. I also developed several websites from scratch, including the designs, and worked on different requirements from these same businesses, such as email marketing and hosting configuration.

HTML/CSS

PHP

jQuery

HTML/CSS

PHP

jQuery

MySQL

CodeIgniter

JavaScript

PROJECTS

Puppeteer automatisms

2021

JavaScript

Puppeteer

JavaScript

Puppeteer