Tag: tsc

I am trying to use tsc in the cli on files in node_modules. Are files in node_modules excluded by default? What should I do?

I am trying to use tsc in the cli on files in node_modules. Are files in node_modules excluded by default? What should I do?

Yes, files in the node_modules directory are excluded by default when using the tsc compiler in the CLI. This is because the node_modules folder typically contains third-party libraries written in JavaScript, which don’t require type checking by the TypeScript compiler.

Here are your options to include files from node_modules:

1. Not Recommended:

  • Directly including node_modules: While technically possible to include the entire node_modules directory in your compilation, it’s strongly discouraged. This can significantly slow down compilation due to the large number of files and potential conflicts with your own project’s code.

2. Recommended approach:

  • Use type definitions: Most popular libraries in node_modules have corresponding type definition packages available on npm (https://www.npmjs.com/). These packages usually start with the @types prefix, followed by the library name (e.g., @types/express). Install the relevant type definition package using npm install @types/<library-name>. This provides type information for the library without including the actual source code.

3. Specific file inclusion (for rare cases):

  • In rare cases, you might need to include specific files from node_modules. While not ideal, you can achieve this by using the --include flag with tsc. However, this should be used with caution, as it can potentially introduce conflicts and dependencies on the external library’s implementation details.

Remember, the best practice is to leverage type definitions whenever possible. They provide type information without unnecessary compilation overhead and maintain a clear separation between your project code and external libraries.

For the command I am using there is little reason to have excluded directories, how can I remove all excluded directories from the settings in tsc cli? No tsconfig.json please.

While you can’t directly remove excluded directories from the CLI, you can achieve a similar effect using the --noResolve flag.

Here’s how to compile a file without any exclusion logic:

Bash
tsc --noResolve your_file.ts

Key points:

  • --noResolve tells the compiler to not perform module resolution, meaning it won’t consider any exclusion patterns or include directives.
  • It’ll only compile the specified file(s) directly.
  • It’s crucial to note that --noResolve has broader implications:
    • No module resolution: References to other modules won’t be resolved, potentially leading to errors if your code depends on external modules.
    • No type checking from included files: Type information from other files won’t be considered, potentially affecting type checking accuracy.

To include specific files:

  • If you need to include files from excluded directories like node_modules, use the --include flag:
Bash
tsc --noResolve --include node_modules/some-library/file.ts your_file.ts

Best practices:

  • Use --noResolve judiciously, as it can bypass intended project structure and type checking.
  • For most scenarios, creating a tsconfig.json file with appropriate include and exclude sections is recommended for better control and maintainability.

Research notes regarding converting JSDoc to TypeScript types

A lot of my JS code had been typed with JSDoc comments.
JSDoc comments are very useful for typing JavaScript code, and also have the benefit of allowing inline TypeScript types and importing TypeScript types from ts files. Types can be checked easily in modern editors such as VSCode. For example, the code below, imports from a ts file and types the variable.

/**
* @type {import('tsfile.ts').MyType}
*
const myVariable = 'abc';

It is also possible to declare the type using @typedef to reuse within the file.

/**
* @typedef {import('tsfile.ts').MyType} MyType
*

/*
* @type {MyType}
*/
const myVariable = 'abc';

However, one big issue with JSDoc is that importing it from external libraries seems to not work.
TypeScript types seem to be usable without any processing by just referencing the file such as:

/**
* @typedef {import('my-library'/ts-file-location.ts).MyType} MyType
*/

For JSDoc, generate type declaration files seems to be required.
This is fine, and is expected for JS projects, but it is an extra step that needs to be prepared for all JS projects.

Considering, TypeScript can be imported into JSDoc in the first place, there is really no reason to store type files using JSDoc. The solution is then to isolate types into type only files in ts, and then export each type. This makes it easy to import into JSDoc and into other projects without and processing.

Searching for solutions to convert JSDoc to TypeScript did take my down and long-winding road of issues, that seems to not have been worth the trouble. I have written any significant information in the notes below, but the solution is to just use tsc from TypeScript. See below.

TypeScript tsc

  • Seems to work best. Just need to add exports if necessary and extract from generated file(s).
# Update [SOURCE] below.
# tsc [SOURCE] --declaration --emitDeclarationOnly --allowJs
#
# Notes:
# -- outFile [BUNDLE_DESTINATION] // Works for only some code, so use optionally. https://www.typescriptlang.org/tsconfig/#outFile
# .d.ts file is created in same location with same name before extension.
# To create ts file with exports, SHOULD remove the ".d" part for declaration file, and replace each "type " with "export type ".
# MAY do the same for "interface", but seems like not used (maybe if specifically specified in JSDOC as interface?).
# To prevent replacing wrong code within comments/strings, etc., check that "type" starts at beginning of line.

Notes

ts-migrate

ts-fix

TypeScript codefixes

Other