Add TypeScript types

[remcohaszing]

The implementation is based on https://github.com/remarkjs/remark/blob/master/packages/remark-stringify/types/index.d.ts

[ChristianMurphy]

Thanks @remcohaszing! 🙇‍♂️
Welcome the Unified! Glad to have you here! 👋
Skimming the changes this looks generally good.
A few tweaks that could help with reviewing:

1. could .ts files be included in the types of files prettier formats? (in the format script in package.json)
2. could dtslint be added to validate the typings?
3. could a types test file be added with some example uses of the plugin in TypeScript?

A recent PR made to remark-toc gives an example of most of these remarkjs/remark-toc#29

[remcohaszing]

Thanks for the quick feedback!

I did the following:

• Change prettier glob to current directory
• Add *.md to .prettierignore, since it wasn’t formatted.
• Format code using Prettier.
• Add TypeScript tests.
• Add dtslint.

xo --fix fails now. I’m not familiar with xo, but I am confused how it is used here. The TypeScript code is linted using both dtslint and xo, which uses @typescript-eslint under the hood. These rules might even conflict, but I can’t verify this, since xo throws:

Error: Error while loading rule '@typescript-eslint/await-thenable': You have used a rule which requires parserServices to be generated. You must therefore provide a value for the "parserOptions.project" property for @typescript-eslint/parser.
Occurred while linting /home/remco/Projects/remark-frontmatter/types/remark-frontmatter-tests.ts
    at Object.getParserServices (/home/remco/Projects/remark-frontmatter/node_modules/@typescript-eslint/experimental-utils/dist/eslint-utils/getParserServices.js:15:15)
    at create (/home/remco/Projects/remark-frontmatter/node_modules/@typescript-eslint/eslint-plugin/dist/rules/await-thenable.js:30:37)
    at Object.create (/home/remco/Projects/remark-frontmatter/node_modules/@typescript-eslint/experimental-utils/dist/eslint-utils/RuleCreator.js:12:24)
    at createRuleListeners (/home/remco/Projects/remark-frontmatter/node_modules/eslint/lib/linter/linter.js:746:21)
    at /home/remco/Projects/remark-frontmatter/node_modules/eslint/lib/linter/linter.js:916:31
    at Array.forEach (<anonymous>)
    at runRules (/home/remco/Projects/remark-frontmatter/node_modules/eslint/lib/linter/linter.js:861:34)
    at Linter._verifyWithoutProcessors (/home/remco/Projects/remark-frontmatter/node_modules/eslint/lib/linter/linter.js:1157:31)
    at Linter._verifyWithoutProcessors (/home/remco/Projects/remark-frontmatter/node_modules/eslint-plugin-eslint-comments/lib/utils/patch.js:165:42)
    at Linter._verifyWithConfigArray (/home/remco/Projects/remark-frontmatter/node_modules/eslint/lib/linter/linter.js:1255:21)

[ChristianMurphy]

I haven't run into that specific error, but on other repo's I've run into random errors with xo and the type definitions.
adding --ignore types to the XO options seems to do the trick.

[ChristianMurphy]

Thanks @remcohaszing !

[wooorm]

Released in 2.0.0. Thanks @remcohaszing!