Javascript tsconfig file (tsconfig.js)

[DanielHoffmann]

Search Terms

config
tsconfig.json

Suggestion

It would be very helpful if typescript followed the conventions of pretty much every other JS-stack tool and allowed the configuration to be done as a javascript file so they can more easily be manipulated.
For example all these tools (and many more) already accept configuration files to be javascript:

Prettier -> .prettierrc.js
Jest -> jest.config.js
Webpack -> webpack.config.js
eslint -> .eslintrc.js
styleling -> .stylelintrc.js
lint-staged -> lint-staged.config.js

My suggestion is for typescript tsconfig resolver to look for a tsconfig.js file if available, if so require() it and use the exported values as configuration. If that file is not available then follow the current resolver rules for tsconfig.json.

Use Cases

• Filesystem introspection
• Better environment variable toggling of options
• Easier extensibility of configurations
• Easier building of tools that include typescript

Examples

module.exports = {
  "includes": [path.resolve(__dirname, process.env.SOURCE_DIR)],
  ...
}

const config = { ... }
if (NODE_ENV === 'development') config.compilerOptions.noUnusedLocals = false
module.exports = config

Right now it is impossible to merge arrays when using the "extends" option of tsconfig.json. If the configuration were javascript files this would be feasible:

const originalConfig = require('some-dep/config/tsconfig.json')
const path = require('path')
module.exports = {
  ...originalConfig,
  includes: [...originalConfig.includes,  path.resolve(__dirname, './mytypes/')]
} 

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

[MartinJohns]

Duplicate of #30400. Used search terms: tsconfig.js

[StJohn3D]

#30400 should have been marked a duplicate of this one. This issue does a much better job of explaining why we need this feature. one tsconfig.json simply doesn't cut it for more complicated projects.

[qodesmith]

Why was this issue closed? This is a fantastic suggestion. I'm looking to dynamically set compilerOptions.paths and with json, that's just impossible.

[ftzi]

Up. Having all the setup json as js files is the future already happening.

[faeb187]

@qodesmith actually it's not impossible, it's very easy 👍
@SrBrahma maybe generating the JSON files is more futuristic 🙏

1. Just read the file using fs.readFile or fs.readFileSync with option { encoding: "utf8" }
2. JSON.parse() the string you get
3. update your JSON however you like dynamically
4. JSON.stringify() the final JSON before...
5. write the file back where it belongs using fs.writeFile or fs.writeFileSync

I was looking if .js is allowed but it's easy to just generate your config files (all of them) then add a CLI or whatever and configure or set some default templates, etc.

[Tofandel]

@faeb187 That would not work if your config includes non encodable content, like functions, which would be the use case for a .js file

[qodesmith]

@Tofandel What @faeb187 is suggesting is manipulating JSON data by reading, updating, and re-writing the data back to disk. Since the source of truth would be a JSON file, there wouldn't be any non-encodable content. It's essentially the same solution I came up with a while ago, but it's still a hack.