Typescript strict mode plugin

Typescript plugin that allows turning on strict mode in specific files or directories.

Do i need this plugin?

This plugin was created for bigger repositories that want to incorporate typescript strict mode, but project is so big that refactoring everything would take ages. This plugin allows user to simply put //@ts-strict comment to a top of a file and turn a strict mode to that file. If needed, strict mode can be turned on to directories too. Plugins in general doesn't work in compile time. They will show errors in your IDE but they won't appear during compilation. To check strict errors in marked files you can use our script tsc-strict. This command line tool is created to check for files that should be checked with strict rules in compilation time. It finds all files with //@ts-strict comment and files specified in paths parameter and checks for strict typescript errors only for that files. Therefore, we have strict errors inside our files and during build time.

How to install

Use npm:

npm i --save-dev typescript-strict-plugin

or yarn

yarn add -D typescript-strict-plugin

and add plugin to your tsconfig.json:

{
 "compilerOptions": {
   ...
   "strict": false,
   "plugins": [
    {
     "name": "typescript-strict-plugin"
    }
   ]
 }
}

That's it! You should be able to use @ts-strict comment to strictly check your files.

Configuration

Plugin takes one extra non-mandatory argument paths that is an array of relative or absolute paths of directories that should be included.

{
  "compilerOptions": {
    ...
    "strict": false,
    "plugins": [
      {
        "name": "typescript-strict-plugin",
        "paths": [
          "./src",
          "/absolute/path/to/source/"
        ]
      }
    ]
  }
}

All files contained in those paths will be strictly checked. Yay!

To add cli tool to your build time you can add a script to scripts list in package.json

{
  "scripts": {
    ...,
    "typecheck": "tsc && tsc-strict",
  },
}

Then you can simply run

yarn tsc-strict

All your strict files should be checked from command line.

You can also pass some tsc arguments to the tsc-strict to override default compiler options e.g.

yarn tsc-strict --strictNullChecks false

would not check for the strict null check in your files. The tsc-strict accepts all the arguments that regular tsc command accepts.

Examples

Let's consider this type and a variable

interface TestType {
   bar: string;
}

const foo: TestType | undefined = undefined;

1. No paths argument With tsconfig.json like this:

{
  "compilerOptions": {
    ...
    "strict": false,
    "plugins": [
      {
        "name": "typescript-strict-plugin"
      }
    ]
  }
}

Typescript will produce errors:

//@ts-strict
...
const boo = foo.bar; // TS2532: Object is possibly 'undefined'.

Or not, depending on whether we used ts-strict or not:

//no strict comment here
...
const boo = foo.bar; // no error here

2. With paths argument With tsconfig.json like this:

{
  "compilerOptions": {
    ...
    "strict": false,
    "plugins": [
      {
        "name": "typescript-strict-plugin",
         "path": "./src"
      }
    ]
  }
}

If file is in the directory typescript will produce errors even if ts-strict comment is not in the file :

// ./src/index.ts
const boo = foo.bar; // TS2532: Object is possibly 'undefined'.

If file is not in the diretory there will be no error

// ./lib/index.ts
const boo = foo.bar; // no error here

If file is not in the diretory but there is ts-strict file will be check with strict mode:

// ./lib/index.ts
//@ts-strict
...
const boo = foo.bar; // TS2532: Object is possibly 'undefined'. 

Testing the plugin

Manually

run

npm i

inside root folder and sample-project folder and then run

npm run build

or

npm run dev

and restart typescript service inside sample-project. Files in sample-project folder should use a local plugin. After you made changes to a plugin you should probably restart typescript service in order to reload the plugin.

Tests

In order to run tests run

npm run test

Contributing

Feel free to create PR's and issues.