TkDodo's blog

The Vertical Codebase

Mon, 13 Apr 2026 00:00:00 GMT

Let's take a look at why the common, horizontal code structure is not ideal, where it breaks down, and what we can do about it.

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Test IDs are an a11y smell

Mon, 23 Mar 2026 00:00:00 GMT

Users don't use data-testid, so why do your tests?

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Creating Query Abstractions

Mon, 23 Feb 2026 00:00:00 GMT

Building reusable abstractions on top of libraries that rely on type inference can be deceptively difficult, which is why we need better ways to build those abstractions ...

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Building Type-Safe Compound Components

Fri, 02 Jan 2026 00:00:00 GMT

Compound Components are great, but should be type-safe. No, this isn't about the children prop ...

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2025 in Review

Fri, 26 Dec 2025 00:00:00 GMT

A retrospective on what has happened for me in 2025

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Designing Design Systems

Mon, 01 Dec 2025 00:00:00 GMT

I want to write more about what makes a good design system. This is the unstructured list of principles I think matter.

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Omit for Discriminated Unions in TypeScript

Mon, 24 Nov 2025 00:00:00 GMT

Why TypeScript’s built-in Omit breaks discriminated unions, and how a distributive version preserves them.

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Tooltip Components Should Not Exist

Mon, 17 Nov 2025 00:00:00 GMT

A look at why tooltip components are often the wrong abstraction in design systems, leading to accessibility issues, misuse, and inconsistent user experiences.

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Context Inheritance in TanStack Router

Sun, 12 Oct 2025 00:00:00 GMT

An overview of how TanStack Router automatically shares and infers path params, search params, and context between nested routes in a type-safe way.

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Deriving Client State from Server State

Mon, 01 Sep 2025 00:00:00 GMT

How to use derived state in React to keep client state and server data aligned without manual sync or effects.

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React Query Selectors, Supercharged

Mon, 04 Aug 2025 00:00:00 GMT

How to get the most out of select, sprinkled with some TypeScript tips.

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The Useless useCallback

Mon, 28 Jul 2025 00:00:00 GMT

Why most memoization is downright useless...

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The Beauty of TanStack Router

Sun, 25 May 2025 00:00:00 GMT

Yes, it's type-safe, but there's so much more to love about TanStack Router.

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Concurrent Optimistic Updates in React Query

Mon, 28 Apr 2025 00:00:00 GMT

How to build optimistic UI that is resilient to race conditions, even when multiple mutations update the same entity concurrently.

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My Open Source Origin Story

Mon, 31 Mar 2025 00:00:00 GMT

A brief story of how I got into Open Source

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2024 in Review

Sun, 29 Dec 2024 00:00:00 GMT

A retrospective on what has happened for me in 2024

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React Query - The Bad Parts

Sat, 28 Dec 2024 00:00:00 GMT

In this talk, maintainer Dominik will explore the other side—the less favorable aspects of React Query and situations where it may not be the best fit. No library is perfect; every choice involves trade-offs. By the end of this talk, you'll have a better understanding of React Query's limitations and why it remains a compelling choice despite them.

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Ref Callbacks, React 19 and the Compiler

Sun, 08 Dec 2024 00:00:00 GMT

Reflecting on useCallback, how the Compiler changed my thinking about it, and what React 19 has in store for Ref Callbacks...

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My Slow Retreat from Twitter

Tue, 03 Dec 2024 00:00:00 GMT

A brief reflection on the platform and how I plan to continue with it...

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React Query API Design - Lessons Learned

Fri, 25 Oct 2024 00:00:00 GMT

In this talk, React Query maintainer Dominik will walk us through some of the API design choices that were made in React Query to get to that DX. You'll hear stories about things that went well, but also about tradeoffs and mistakes that were made, and what lessons we can all learn from those.

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Component Composition is great btw

Sat, 21 Sep 2024 00:00:00 GMT

Component composition is one of the best parts of React, and I think we should take more time to break our components into manageable parts before littering one component with conditional renderings.

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How Infinite Queries work

Sat, 14 Sep 2024 00:00:00 GMT

A serious bug report about infinite queries led me to question it's architecture, but it all turned out fine in the end ...

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Introducing XState Store

Thu, 01 Aug 2024 00:00:00 GMT

There's a new state manager in the game, and it ticks all my boxes ...

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Please Stop Using Barrel Files

Fri, 26 Jul 2024 00:00:00 GMT

Why you probably shouldn't be adding index.ts files everywhere

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React 19 and Suspense - A Drama in 3 Acts

Sun, 16 Jun 2024 00:00:00 GMT

React 19 is a very promising release - but there's something not quite right yet with suspense...

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Automatic Query Invalidation after Mutations

Sat, 25 May 2024 00:00:00 GMT

Even though there is nothing built into React Query, it doesn't need a lot of code to implement automatic query invalidation in user-land thanks to the global cache callbacks.

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Zustand and React Context

Sun, 14 Apr 2024 00:00:00 GMT

Zustand stores a global and don't need React Context - but sometimes, it makes sense to combine them regardless.

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Avoiding Hydration Mismatches with useSyncExternalStore

Wed, 21 Feb 2024 00:00:00 GMT

Avoiding hydration mismatches can usually be done in two ways - suppressing the warning or spawning an effect. But is there a third option ... ?

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The Query Options API

Wed, 17 Jan 2024 00:00:00 GMT

v5 brought a new, powerful API, especially if you're using React Query with TypeScript...

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2023 in Review

Sat, 30 Dec 2023 00:00:00 GMT

A retrospective on what has happened for me in 2023

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Why You Want React Query

Tue, 07 Nov 2023 00:00:00 GMT

Let's take a look at why you'd want a library like React Query, even if you don't need all the extra features it provides...

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The Uphill Battle of Memoization

Sat, 30 Sep 2023 00:00:00 GMT

Exploring why React.memo shouldn't be your first choice for performance optimizations

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Array Types in TypeScript

Sat, 19 Aug 2023 00:00:00 GMT

is string[] really better than Array? Of course not!

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React Query and React Context

Sat, 22 Jul 2023 00:00:00 GMT

Can it make sense to combine React Query with React Context ? Yes, sometimes ...

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Thinking in React Query

Wed, 07 Jun 2023 00:00:00 GMT

In this talk, we will learn how a different mindset can help us understand React Query and work with it efficiently.

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You Might Not Need React Query

Sat, 20 May 2023 00:00:00 GMT

React Query is a great library, but like any tool, you should choose it for the right problem

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Breaking React Query's API on purpose

Sun, 16 Apr 2023 00:00:00 GMT

Why good API design matters, even if it means breaking existing APIs in the face of resistance.

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OSS Feature Decision Tree

Sat, 18 Feb 2023 00:00:00 GMT

An outline of the questions I try to ask myself before adding new features

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Why React isn't dying

Sun, 29 Jan 2023 00:00:00 GMT

Finishing my train of thought about why React is here to stay (for now).

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Type-safe React Query

Sat, 07 Jan 2023 00:00:00 GMT

About the difference between "having types" and "being type-safe"...

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2022 in Review

Sat, 31 Dec 2022 00:00:00 GMT

A retrospective on what has happened for me in 2022

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Inside React Query

Sat, 03 Dec 2022 00:00:00 GMT

Taking a look under the hood of React Query

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Working with Zustand

Sun, 20 Nov 2022 00:00:00 GMT

Let's dive into some tips for working with Zustand - one of my favourite client state management libraries in React.

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Refactor impactfully

Sun, 13 Nov 2022 00:00:00 GMT

Why not every refactoring is worth doing...

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Seeding the Query Cache

Sat, 22 Oct 2022 00:00:00 GMT

With suspense for data fetching on the horizon, it is now more important than ever to make sure your cache is seeded properly to avoid fetch waterfalls.

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Refs, Events and Escape Hatches

Sat, 17 Sep 2022 00:00:00 GMT

Refs can provide a way to sidestep dependency arrays without violating any rules, and the proposed useEvent hook might make working with functions and effects a lot easier...

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React Query meets React Router

Sun, 28 Aug 2022 00:00:00 GMT

React Query and React Router are a match made in heaven.

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Avoiding useEffect with callback refs

Sun, 14 Aug 2022 00:00:00 GMT

Interacting with DOM nodes doesn't necessarily need useEffect

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React Query FAQs

Fri, 24 Jun 2022 00:00:00 GMT

Answering the most frequently asked React Query questions

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Hooks, Dependencies and Stale Closures

Sun, 24 Apr 2022 00:00:00 GMT

Let's demystify what stale closures are in combination with react hooks with the help of the analogy of taking a photo ...

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React Query and Forms

Sun, 10 Apr 2022 00:00:00 GMT

Forms tend to blur the line between server and client state, so let's see how that plays together with React Query.

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Use Urgency

Fri, 25 Mar 2022 00:00:00 GMT

Getting huge refactorings going is not an easy task, but urgency can help here.

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optional vs. undefined

Sat, 19 Feb 2022 00:00:00 GMT

There is a subtle difference between optional fields and required, but potentially undefined ones.

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Offline React Query

Sat, 05 Feb 2022 00:00:00 GMT

A glimpse at what v4 will bring for offline queries

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Always provide customer value

Sat, 29 Jan 2022 00:00:00 GMT

Finding the right spot for doing a refactoring can be tricky

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Road to Refactoring

Sat, 22 Jan 2022 00:00:00 GMT

A blogpost series about patterns that have helped me succeed with refactorings

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2021 in Review

Tue, 21 Dec 2021 00:00:00 GMT

A retrospective on what has happened for me in 2021

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Beware the leaking any

Sat, 04 Dec 2021 00:00:00 GMT

Any is not among my favourite TypeScript types, but it is the one you will inevitably encounter. Let's see what makes it so dangerous.

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Leveraging the Query Function Context

Tue, 26 Oct 2021 00:00:00 GMT

Use what React Query provides for optimal type safety

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Mastering Mutations in React Query

Sat, 09 Oct 2021 00:00:00 GMT

Learn all about the concept of performing side effects on the server with React Query.

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useState vs useReducer

Sun, 26 Sep 2021 00:00:00 GMT

To useState or useReducer, that is the question...

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React Query Error Handling

Fri, 10 Sep 2021 00:00:00 GMT

After covering the sunshine cases of data fetching, it's time to look at situations where things don't go as planned and "Something went wrong..."

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React Query as a State Manager

Fri, 20 Aug 2021 00:00:00 GMT

Everything you need to know to make React Query your single source of truth state manager for your async state

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Placeholder and Initial Data in React Query

Mon, 09 Aug 2021 00:00:00 GMT

Learn about the different possibilities to avoid loading spinners in React Query.

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About async functions

Fri, 23 Jul 2021 00:00:00 GMT

A deep dive into async functions and how they are different from promise chaining

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Effective React Query Keys

Sun, 13 Jun 2021 00:00:00 GMT

Learn how to structure React Query Keys effectively as your App grows

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Using WebSockets with React Query

Sun, 06 Jun 2021 00:00:00 GMT

A step-by-step guide on how to make real-time notifications work with react-query

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React Query and TypeScript

Sun, 16 May 2021 00:00:00 GMT

Combine two of the most powerful tools for React Apps to produce great user experience, developer experience and type safety.

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How can I ... ?

Sat, 24 Apr 2021 00:00:00 GMT

Asking the right questions is a form of art that needs to be mastered.

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Testing React Query

Sun, 04 Apr 2021 00:00:00 GMT

Let's take a look at how to efficiently test custom useQuery hooks and components using them.

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Status Checks in React Query

Sat, 27 Mar 2021 00:00:00 GMT

How the wrong status check order can negatively impact user experience

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React Query Render Optimizations

Sat, 20 Mar 2021 00:00:00 GMT

An advanced guide to minimize component re-renderings when using React Query

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useState for one-time initializations

Fri, 12 Mar 2021 00:00:00 GMT

Why you shouldn't rely on useMemo for guaranteed referential stability but prefer useState instead

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React Query Data Transformations

Wed, 10 Mar 2021 00:00:00 GMT

Learn the possibilities to perform the quite common and important task of transforming your data with react-query

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No love for boolean parameters

Sun, 28 Feb 2021 00:00:00 GMT

Innocent looking boolean parameters, or flags, are often the reason for hard to maintain legacy code. Resist the urge of adding them!

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Things to know about useState

Sat, 13 Feb 2021 00:00:00 GMT

5 things everyone needs to know about useState

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Simplifying useEffect

Sat, 23 Jan 2021 00:00:00 GMT

useEffect hooks can be hard to reason about, but I have 5 principles that can help to manage them

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Flow to TypeScript migration journey

Mon, 04 Jan 2021 00:00:00 GMT

How we migrated over 100k lines of code from Flow to TypeScript. A Journey.

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On naming things

Tue, 08 Dec 2020 00:00:00 GMT

Naming is hard. Naming is subjective. Yet there are some things we can objectively do when it comes to finding proper names.

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Practical React Query

Mon, 16 Nov 2020 00:00:00 GMT

Let me share with you the experiences I have made lately with React Query. Fetching data in React has never been this delightful...

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Avoiding legacy systems

Sun, 01 Nov 2020 00:00:00 GMT

Every software will eventually become a nightmare to maintain, unless we actively do something about it.

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Putting props to useState

Sun, 25 Oct 2020 00:00:00 GMT

Part deux of the useState pitfalls series is here, showing patterns to help solve the common use-case of initializing state with a prop.

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The power of const assertions

Thu, 08 Oct 2020 00:00:00 GMT

const assertions are a criminally underused TypeScript feature - learn all about them here, now

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Pedantic index signatures in TypeScript 4.1

Sun, 20 Sep 2020 00:00:00 GMT

Accessing objects and arrays has never been safe in TypeScript, but this is about to change ...

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Why I don't like reduce

Wed, 09 Sep 2020 00:00:00 GMT

If you know me, you know I'm no fan of Array.reduce. I'll explain why in detail in this post.

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Calling JavaScript from TypeScript

Fri, 04 Sep 2020 00:00:00 GMT

Gradually migrating from JS to TS is not without difficulties - here are some tricks to smoothen the interoperability

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Solving conflicts in package-lock.json

Wed, 02 Sep 2020 00:00:00 GMT

Why you should never delete package-lock.json and how npm can solve the conflicts for you

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Don't over useState

Sat, 29 Aug 2020 00:00:00 GMT

The first part of the useState pitfalls series is all about avoiding state altogether. Lots of things might not even be state after all...

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Exhaustive matching in TypeScript

Sun, 09 Aug 2020 00:00:00 GMT

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