loose-ts-check
Version:
Run TS type-check and ignore certain errors in some files
158 lines (104 loc) • 4.37 kB
Markdown
# Loose TS check
[](https://www.npmjs.com/package/loose-ts-check)
[](https://www.npmjs.com/package/loose-ts-check)
[](https://github.com/Gelio/loose-ts-check/blob/master/LICENSE.md)
[](https://github.com/Gelio/loose-ts-check)
The `loose-ts-check` utility helps ignore particular types of TS error in
specified files.
This is useful when migrating to a stricter `tsconfig.json` configuration
incrementally, where only some existing files are allowed to have TS errors.
## Features
- ignores specific TS errors from specific files
- detects files that no longer have to be loosely type-checked
- auto-updates the loosely type-checked list of files when a file no longer has
errors
- auto-updates the ignored error codes when there are no errors of that type
- loosely type-checked files can be specified using globs
## Why not `exclude` in `tsconfig.json`
The `exclude` option in `tsconfig.json` only tells tsc to not start
type-checking from those files. If some already type-checked file imports a file
listed in the `exclude`, it will still be type-checked.
Thus, it does not suit this use case.
## Why not follow the idea from the VSCode project
[The vscode team have already encountered a similar problem](https://code.visualstudio.com/blogs/2019/05/23/strict-null#_coming-up-with-an-incremental-plan)
and solved it in another way. They created a new `tsconfig.json` that only
included some files.
While this works great with existing files, it does not automatically enforce a
stricter config for new files in the project.
## Installation
Install the utility with:
```sh
npm install loose-ts-check --save-dev
```
## Usage
Pipe the result of `tsc` to `loose-ts-check` to run the utility:
```sh
tsc --noEmit -p tsconfig.strict.json | npx loose-ts-check
```
To initialize the list of ignored errors and loosely type-checked files based on
the current errors, run:
```sh
tsc --noEmit -p tsconfig.strict.json | npx loose-ts-check --init
```
To automatically update the list of loosely type-checked files, run:
```sh
tsc --noEmit -p tsconfig.strict.json | npx loose-ts-check --auto-update
```
### Options
Display the list of options by running:
```sh
npx loose-ts-check --help
```
## Recipes
### Reusing the same tsc output
To avoid running `tsc` again and again when testing, save the output to a file:
```ts
tsc > errors.log;
```
And then, use the tool by redirecting the input:
```sh
npx loose-ts-check < errors.log
```
### Migrating to a stricter tsconfig.json
To migrate the codebase to use a stricter `tsconfig.json`, you will need 2
tsconfigs:
1. `tsconfig.json` - the strict tsconfig. This config will be used by the IDE
and by the `loose-ts-check` tool.
The aim is to see the errors in the IDE, to feel motivated to fix the errors
while modifying existing files.
2. `tsconfig.loose.json` - a tsconfig that extends `tsconfig.json`, but has the
stricter options turned off.
This config will be used by any linter, test runner, bundler you will have.
If you are using `ts-node`, you need to pass `tsconfig.loose.json` as a
`TS_NODE_PROJECT` variable, so it uses the correct tsconfig, e.g.
```sh
cross-env TS_NODE_PROJECT="tsconfig.loose.json" webpack --mode=development
```
To run `tsc` to do type-checking, pass `-p tsconfig.loose.json` option:
```sh
tsc -p tsconfig.loose.json
```
Then, use the following command to initialize the config files:
```sh
tsc | npx loose-ts-check --init
```
After that, run
```sh
tsc | npx loose-ts-check
```
instead of `tsc` to do type-checking.
## IDE plugin
In case you want to have the errors ignored in your IDE as well, use
[loose-ts-check-plugin](https://github.com/nwetzel22/loose-ts-check-plugin).
## Development
To verify the correctness, run:
```sh
npm run type-check
npm run lint:formatting
npm run test
```
## Contributing
Contributions are welcome!
Make sure the CI passes on your PRs, and that your code is covered by unit
tests.