Toru Kobayashi
Web Developer at mercari
Japan
Summary
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RockstarToru Kobayashi is a web developer based in Japan with 16 years of hands-on experience building and refining React-based applications and developer tools. He contributes to major open-source projects such as React, Next.js, SWR, Enzyme, and react-dates, focusing on bug fixes, refactors, accessibility, and testing improvements that raise long-term maintainability. Toru’s work spans both front-end component design and full-stack framework issues, showing an ability to move between UX details (aria labels, AppBar/Modal behavior) and framework-level fixes (App Router, asset handling). He has a track record of removing legacy code and adding runtime deprecation warnings—small changes that reduce technical debt for large ecosystems. Colleagues likely value him for pragmatic, test-first improvements that quietly improve developer and user experience across widely used libraries.
15 years of coding experience
Github Skills (40)
accessibility10
hook10
javascript10
component-design10
fetchr10
jes10
testing10
css10
fetcher10
typescript10
nextjs10
styled-components10
ui-design10
enzyme-testing10
uid10
Programming languages (13)
Github contributions (5)
reactjs/react-transition-group
Feb 2017 - Aug 2022
An easy way to perform animations when a React component enters or leaves the DOM
Role in this project:
Front-end Developer
Front-end DeveloperContributions:21 reviews, 41 commits, 92 PRs in 5 years 6 months
Contributions summary:Toru primarily contributed to the React Transition Group library by addressing bugs, improving documentation, and implementing new features. Their work involved fixing lint errors, modifying component behavior for animation, and optimizing the transition process for enter animations. They also focused on ensuring correct prop handling and updating documentation to reflect the library's functionality.
transitioneasing-functionsreactjspage-transitionsjavascript
vercel/swr
Jan 2021 - Jan 2023
React Hooks for Data Fetching
Role in this project:Front-end Developer
Front-end DeveloperContributions:91 reviews, 83 commits, 101 PRs in 2 years
Contributions summary:Toru primarily contributed to the `vercel/swr` repository, which focuses on React Hooks for data fetching. The commits demonstrate a focus on code refactoring and bug fixes related to the core functionalities of the SWR library. The user improved component re-renders and addressed dependency warnings. Moreover, they added tests for useSWRInfinite and fixed flaky tests.
stale-while-revalidatedata-exchangereactdatareact-native
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