Please always add default values to `tsconfig.json` documentation

[SetTrend]

🔍 Search Terms

tsconfig.json default values options

✅ Viability Checklist

• 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, new syntax sugar for JS, etc.)
• This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
• This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

⭐ Suggestion

Many of the tsconfig.json options documented at https://www.typescriptlang.org/tsconfig/ do not specify their default values. So, programmers are left to either guess or add dozens of configuration properties to make sure things will run smoothly.

Please, add default value information to every single tsconfig.json option at https://www.typescriptlang.org/tsconfig/

📃 Motivating Example

./.

💻 Use Cases

Every time a TypeScript project is to be configured.

[mkantor]

I think this belongs in microsoft/TypeScript-Website, though note what the issue template says in that repository: pull requests are strongly preferred to issues.

[mkantor]

Also note that many of the defaults are not simple static values, but derived via logic based on other config values. For example you can see include's default is documented as "[] if files is specified; **/* otherwise".

Hopefully none of the logic is too complex to be succinctly described though. I do agree it would be nice if more of the defaults were documented there.

[SetTrend]

@mkantor:

I think this belongs in microsoft/TypeScript-Website,

I apprehend. Yet, I believe that repository has reached a stale state, as posted in microsoft/TypeScript-Website/issues/2804.

Also note that many of the defaults are not simple static values

I understand that. However, it should still be possible to explain what the default is, depending on related properties.

I raised this issue here because only the TypeScript developers can tell the defaults they have implemented. We users cannot know them without joining the team and getting paid for it. Good documentation is crucial when distributing configuration properties in the wild.

[RyanCavanaugh]

I raised this issue here because only the TypeScript developers can tell the defaults they have implemented. We users cannot know them without joining the team and getting paid for it.

When we're asked what the computed default is, I am not making this up, we go read the source code, which is open...

[MartinJohns]

Duplicate of #48441, your own issue.

[SetTrend]

Oh, my mistake.

Apparently, nothing has improved yet.

I'm not confident about how the TSConfig reference page is built. Perhaps a commit hook or a linter step added to the pnpm run --filter=tsconfig-reference generate-json script would help, preventing commits or updates to the documentation if a description for default values is missing for any of the configuration parameters.