TypeScript

React Query is now written in TypeScript to make sure the library and your projects are type-safe!

Install the latest version to get React Query with the new types:

 npm install react-query --save

Changes

• The query results are no longer discriminated unions, which means you have to check the actual data and error properties.
• Requires TypeScript v3.8 or greater

Defining Custom Hooks

When defining a custom hook you need to specify the result and error types, for example:

1 export function useGroups() {
2   return useQuery<Group[], Error>(
3     'list-groups',
4     () => fetch(`/api/groups`).then(res => res.json())
5   )
6 }