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* Remove distinction between long, short transitions We're removing the `timeoutMs` option, so there's no longer any distinction between "short" and "long" transitions. They're all treated the same. This commit doesn't remove `timeoutMs` yet, only combines the internal priority levels. * Disable `timeoutMs` argument tl;dr ----- - We're removing the `timeoutMs` argument from `useTransition`. - Transitions will either immediately switch to a skeleton/placeholder view (when loading new content) or wait indefinitely until the data resolves (when refreshing stale content). - This commit disables the `timeoutMS` so that the API has the desired semantics. It doesn't yet update the types or migrate all the test callers. I'll do those steps in follow-up PRs. Motivation ---------- Currently, transitions initiated by `startTransition` / `useTransition` accept a `timeoutMs` option. You can use this to control the maximum amount of time that a transition is allowed to delay before we give up and show a placeholder. What we've discovered is that, in practice, every transition falls into one of two categories: a **load** or a **refresh**: - **Loading a new screen**: show the next screen as soon as possible, even if the data hasn't finished loading. Use a skeleton/placeholder UI to show progress. - **Refreshing a screen that's already visible**: keep showing the current screen indefinitely, for as long as it takes to load the fresh data, even if the current data is stale. Use a pending state (and maybe a busy indicator) to show progress. In other words, transitions should either *delay indefinitely* (for a refresh) or they should show a placeholder *instantly* (for a load). There's not much use for transitions that are delayed for a small-but-noticeable amount of time. So, the plan is to remove the `timeoutMs` option. Instead, we'll assign an effective timeout of `0` for loads, and `Infinity` for refreshes. The mechanism for distinguishing a load from a refresh already exists in the current model. If a component suspends, and the nearest Suspense boundary hasn't already mounted, we treat that as a load, because there's nothing on the screen. However, if the nearest boundary is mounted, we treat that as a refresh, since it's already showing content. If you need to fix a transition to be treated as a load instead of a refresh, or vice versa, the solution will involve rearranging the location of your Suspense boundaries. It may also involve adding a key. We're still working on proper documentation for these patterns. In the meantime, please reach out to us if you run into problems that you're unsure how to fix. We will remove `timeoutMs` from `useDeferredValue`, too, and apply the same load versus refresh semantics to the update that spawns the deferred value. Note that there are other types of delays that are not related to transitions; for example, we will still throttle the appearance of nested placeholders (we refer to this as the placeholder "train model"), and we may still apply a Just Noticeable Difference heuristic (JND) in some cases. These aren't going anywhere. (Well, the JND heuristic might but for different reasons than those discussed above.) |
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| __tests__ | ||
| codes.json | ||
| extract-errors.js | ||
| invertObject.js | ||
| README.md | ||
| transform-error-messages.js | ||
| Types.js | ||
The error code system substitutes React's error messages with error IDs to provide a better debugging support in production. Check out the blog post here.
codes.jsoncontains the mapping from IDs to error messages. This file is generated by the Gulp plugin and is used by both the Babel plugin and the error decoder page in our documentation. This file is append-only, which means an existing code in the file will never be changed/removed.extract-errors.jsis an node script that traverses our codebase and updatescodes.json. You can test it by runningyarn extract-errors.transform-error-messagesis a Babel pass that rewrites error messages to IDs for a production (minified) build.