Jeroen Claassens
Software Engineer - Niet Beschikbaar Voor Andere Functies at CGI Nederland
Delft, South Holland, Netherlands
Summary
🤩
Rockstar🎓
Top SchoolJeroen Claassens is a seasoned full-stack software engineer based in Delft with a decade of experience building robust JavaScript and Java systems for enterprise and open-source projects. Currently at CGI Nederland, he blends backend craftsmanship—evident from contributions to discord.js and Commando—with front-end finesse, including work on react-if and numerous TypeScript definitions in DefinitelyTyped. He co-owns the Skyra project and manages SapphireDev, showing leadership in large community-driven tooling for the Discord ecosystem. Known for pragmatic refactors, stronger typings, and improving developer ergonomics (like programmatic npm APIs and changelog tooling), he consistently strengthens both runtime behavior and developer DX. Outside work he pairs a penchant for rapid adoption of new techniques with a practical focus on reliable, well-tested implementations.
10 years of coding experience
Create A High End Video Game (minor), Create A High End Video Game (minor) at Hogeschool van Arnhem en Nijmegen (HAN)Bachelor of Science - BS, Computer Software Engineering, Bachelor of Science - BS, Computer Software Engineering at De Haagse Hogeschool / The Hague University of Applied Sciences
Dutch, English
Stackoverflow
341reputation
7kreached
9answers
6questions
Github Skills (50)
conventional-commits10
typesc10
javascript10
npm10
discord-js10
discord10
component-development10
command-line-interface10
typescript10
type-definition10
type-system10
testing-library10
react-testing-library10
react-testing10
jestjs10
Programming languages (25)
Github contributions (5)
romac/react-if
Oct 2020 - Jan 2023
🌗 Render React components conditionally
Role in this project:
Front-end Developer
Front-end DeveloperContributions:8 releases, 17 reviews, 105 commits in 2 years 3 months
Contributions summary:Jeroen primarily contributed to the `react-if` repository, a library for conditionally rendering React components. Their work included refactoring code, standardizing functions, and fixing import paths. They also wrote and updated unit tests to cover various cases and improve the library's reliability, including a test suite for the `<Switch>` component. Additionally, they added TSDoc comments.
renderreactreact-renderhigher-order-componentreact-components
discordjs/discord.js
Apr 2018 - Nov 2022
A powerful JavaScript library for interacting with the Discord API
Role in this project:Back-end Developer
Back-end DeveloperContributions:19 reviews, 16 commits, 29 PRs in 4 years 8 months
Contributions summary:Jeroen primarily contributed to the back-end functionality of the Discord.js library, with a focus on enhancing and adding features to the channel and activity structures. They introduced a manageable getter for `GuildChannel` and added support for the `CUSTOM_STATUS` activity type. The user also made improvements to type definitions and utility formatters, demonstrating a good understanding of the library's internal structure. Several commits focused on refactoring and expanding the library's type definitions.
apidiscord-jsjavascript-librarydiscorddiscordjs
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