Compile invariant directly to throw expressions (#15071)
* Transform invariant to custom error type
This transforms calls to the invariant module:
```js
invariant(condition, 'A %s message that contains %s', adj, noun);
```
Into throw statements:
```js
if (!condition) {
if (__DEV__) {
throw ReactError(`A ${adj} message that contains ${noun}`);
} else {
throw ReactErrorProd(ERR_CODE, adj, noun);
}
}
```
The only thing ReactError does is return an error whose name is set
to "Invariant Violation" to match the existing behavior.
ReactErrorProd is a special version used in production that throws
a minified error code, with a link to see to expanded form. This
replaces the reactProdInvariant module.
As a next step, I would like to replace our use of the invariant module
for user facing errors by transforming normal Error constructors to
ReactError and ReactErrorProd. (We can continue using invariant for
internal React errors that are meant to be unreachable, which was the
original purpose of invariant.)
* Use numbers instead of strings for error codes
* Use arguments instead of an array
I wasn't sure about this part so I asked Sebastian, and his rationale
was that using arguments will make ReactErrorProd slightly slower, but
using an array will likely make all the functions that throw slightly
slower to compile, so it's hard to say which way is better. But since
ReactErrorProd is in an error path, and fewer bytes is generally better,
no array is good.
* Casing nit
2019-03-19 04:58:03 +08:00
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The error code system substitutes React's error messages with error IDs to
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provide a better debugging support in production. Check out the blog post
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[here](https://reactjs.org/blog/2016/07/11/introducing-reacts-error-code-system.html).
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2016-11-09 04:20:46 +08:00
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Compile invariant directly to throw expressions (#15071)
* Transform invariant to custom error type
This transforms calls to the invariant module:
```js
invariant(condition, 'A %s message that contains %s', adj, noun);
```
Into throw statements:
```js
if (!condition) {
if (__DEV__) {
throw ReactError(`A ${adj} message that contains ${noun}`);
} else {
throw ReactErrorProd(ERR_CODE, adj, noun);
}
}
```
The only thing ReactError does is return an error whose name is set
to "Invariant Violation" to match the existing behavior.
ReactErrorProd is a special version used in production that throws
a minified error code, with a link to see to expanded form. This
replaces the reactProdInvariant module.
As a next step, I would like to replace our use of the invariant module
for user facing errors by transforming normal Error constructors to
ReactError and ReactErrorProd. (We can continue using invariant for
internal React errors that are meant to be unreachable, which was the
original purpose of invariant.)
* Use numbers instead of strings for error codes
* Use arguments instead of an array
I wasn't sure about this part so I asked Sebastian, and his rationale
was that using arguments will make ReactErrorProd slightly slower, but
using an array will likely make all the functions that throw slightly
slower to compile, so it's hard to say which way is better. But since
ReactErrorProd is in an error path, and fewer bytes is generally better,
no array is good.
* Casing nit
2019-03-19 04:58:03 +08:00
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- [`codes.json`](https://github.com/facebook/react/blob/master/scripts/error-codes/codes.json)
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contains the mapping from IDs to error messages. This file is generated by the
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Gulp plugin and is used by both the Babel plugin and the error decoder page in
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our documentation. This file is append-only, which means an existing code in
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the file will never be changed/removed.
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- [`extract-errors.js`](https://github.com/facebook/react/blob/master/scripts/error-codes/extract-errors.js)
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is an node script that traverses our codebase and updates `codes.json`. You
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Lint rule for unminified errors (#15757)
* Lint rule for unminified errors
Add a lint rule that fails if an invariant message is not part of the
error code map.
The goal is to be more disciplined about adding and modifiying
production error codes. Error codes should be consistent across releases
even if their wording changes, for continuity in logs.
Currently, error codes are added to the error code map via an automated
script that runs right before release. The problem with this approach is
that if someone modifies an error message in the source, but neglects to
modify the corresponding message in the error code map, then the message
will be assigned a new error code, instead of reusing the existing one.
Because the error extraction script only runs before a release, people
rarely modify the error code map in practice. By moving the extraction
step to the PR stage, it forces the author to consider whether the
message should be assigned a new error code. It also allows the reviewer
to review the changes.
The trade off is that it requires more effort and context to land new
error messages, or to modify existing ones, particular for new
contributors who are not familiar with our processes.
Since we already expect users to lint their code, I would argue the
additional burden is marginal. Even if they forget to run the lint
command locally, they will get quick feedback from the CI lint job,
which typically finishes within 2-3 minutes.
* Add unreleased error messages to map
2019-05-30 02:29:04 +08:00
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can test it by running `yarn extract-errors`.
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2019-08-28 22:49:45 +08:00
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- [`transform-error-messages`](https://github.com/facebook/react/blob/master/scripts/error-codes/transform-error-messages.js)
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Compile invariant directly to throw expressions (#15071)
* Transform invariant to custom error type
This transforms calls to the invariant module:
```js
invariant(condition, 'A %s message that contains %s', adj, noun);
```
Into throw statements:
```js
if (!condition) {
if (__DEV__) {
throw ReactError(`A ${adj} message that contains ${noun}`);
} else {
throw ReactErrorProd(ERR_CODE, adj, noun);
}
}
```
The only thing ReactError does is return an error whose name is set
to "Invariant Violation" to match the existing behavior.
ReactErrorProd is a special version used in production that throws
a minified error code, with a link to see to expanded form. This
replaces the reactProdInvariant module.
As a next step, I would like to replace our use of the invariant module
for user facing errors by transforming normal Error constructors to
ReactError and ReactErrorProd. (We can continue using invariant for
internal React errors that are meant to be unreachable, which was the
original purpose of invariant.)
* Use numbers instead of strings for error codes
* Use arguments instead of an array
I wasn't sure about this part so I asked Sebastian, and his rationale
was that using arguments will make ReactErrorProd slightly slower, but
using an array will likely make all the functions that throw slightly
slower to compile, so it's hard to say which way is better. But since
ReactErrorProd is in an error path, and fewer bytes is generally better,
no array is good.
* Casing nit
2019-03-19 04:58:03 +08:00
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is a Babel pass that rewrites error messages to IDs for a production
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(minified) build.
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