# remark-lint-no-tabs [![Build][badge-build-image]][badge-build-url] [![Coverage][badge-coverage-image]][badge-coverage-url] [![Downloads][badge-downloads-image]][badge-downloads-url] [![Size][badge-size-image]][badge-size-url] [![Sponsors][badge-funding-sponsors-image]][badge-funding-url] [![Backers][badge-funding-backers-image]][badge-funding-url] [![Chat][badge-chat-image]][badge-chat-url] [`remark-lint`][github-remark-lint] rule to warn when tabs are used. ## Contents * [What is this?](#what-is-this) * [When should I use this?](#when-should-i-use-this) * [Presets](#presets) * [Install](#install) * [Use](#use) * [API](#api) * [`unified().use(remarkLintNoTabs)`](#unifieduseremarklintnotabs) * [Recommendation](#recommendation) * [Fix](#fix) * [Examples](#examples) * [Compatibility](#compatibility) * [Contribute](#contribute) * [License](#license) ## What is this? This package checks for tabs. ## When should I use this? You can use this package to check tabs. ## Presets This plugin is not included in presets maintained here. ## Install This package is [ESM only][github-gist-esm]. In Node.js (version 16+), install with [npm][npm-install]: ```sh npm install remark-lint-no-tabs ``` In Deno with [`esm.sh`][esm-sh]: ```js import remarkLintNoTabs from 'https://esm.sh/remark-lint-no-tabs@4' ``` In browsers with [`esm.sh`][esm-sh]: ```html ``` ## Use On the API: ```js import remarkLint from 'remark-lint' import remarkLintNoTabs from 'remark-lint-no-tabs' import remarkParse from 'remark-parse' import remarkStringify from 'remark-stringify' import {read} from 'to-vfile' import {unified} from 'unified' import {reporter} from 'vfile-reporter' const file = await read('example.md') await unified() .use(remarkParse) .use(remarkLint) .use(remarkLintNoTabs) .use(remarkStringify) .process(file) console.error(reporter(file)) ``` On the CLI: ```sh remark --frail --use remark-lint --use remark-lint-no-tabs . ``` On the CLI in a config file (here a `package.json`): ```diff … "remarkConfig": { "plugins": [ … "remark-lint", + "remark-lint-no-tabs", … ] } … ``` ## API This package exports no identifiers. It exports no additional [TypeScript][typescript] types. The default export is [`remarkLintNoTabs`][api-remark-lint-no-tabs]. ### `unified().use(remarkLintNoTabs)` Warn when tabs are used. ###### Parameters There are no options. ###### Returns Transform ([`Transformer` from `unified`][github-unified-transformer]). ## Recommendation Regardless of the debate in other languages of whether to use tabs versus spaces, when it comes to markdown, tabs do not work as expected. Largely around things such as block quotes, lists, and indented code. Take for example block quotes: `>\ta` gives a paragraph with the text `a` in a blockquote, so one might expect that `>\t\ta` results in indented code with the text `a` in a block quote. ```markdown >\ta >\t\ta ``` Yields: ```html

a

``` Because markdown uses a hardcoded tab size of 4, the first tab could be represented as 3 spaces (because there’s a `>` before). One of those “spaces” is taken because block quotes allow the `>` to be followed by one space, leaving 2 spaces. The next tab can be represented as 4 spaces, so together we have 6 spaces. The indented code uses 4 spaces, so there are two spaces left, which are shown in the indented code. ## Fix [`remark-stringify`](https://github.com/remarkjs/remark/tree/main/packages/remark-stringify) uses spaces exclusively for indentation. ## Examples ##### `ok.md` ###### In ```markdown ␠␠␠␠mercury() ``` ###### Out No messages. ##### `not-ok.md` ###### In ```markdown ␉mercury() Venus␉and Earth. ``` ###### Out ```text 1:1: Unexpected tab (`\t`), expected spaces 3:6: Unexpected tab (`\t`), expected spaces ``` ## Compatibility Projects maintained by the unified collective are compatible with maintained versions of Node.js. When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line, `remark-lint-no-tabs@4`, compatible with Node.js 16. ## Contribute See [`contributing.md`][github-dotfiles-contributing] in [`remarkjs/.github`][github-dotfiles-health] for ways to get started. See [`support.md`][github-dotfiles-support] for ways to get help. This project has a [code of conduct][github-dotfiles-coc]. By interacting with this repository, organization, or community you agree to abide by its terms. ## License [MIT][file-license] © [Titus Wormer][author] [api-remark-lint-no-tabs]: #unifieduseremarklintnotabs [author]: https://wooorm.com [badge-build-image]: https://github.com/remarkjs/remark-lint/workflows/main/badge.svg [badge-build-url]: https://github.com/remarkjs/remark-lint/actions [badge-chat-image]: https://img.shields.io/badge/chat-discussions-success.svg [badge-chat-url]: https://github.com/remarkjs/remark/discussions [badge-coverage-image]: https://img.shields.io/codecov/c/github/remarkjs/remark-lint.svg [badge-coverage-url]: https://codecov.io/github/remarkjs/remark-lint [badge-downloads-image]: https://img.shields.io/npm/dm/remark-lint-no-tabs.svg [badge-downloads-url]: https://www.npmjs.com/package/remark-lint-no-tabs [badge-funding-backers-image]: https://opencollective.com/unified/backers/badge.svg [badge-funding-sponsors-image]: https://opencollective.com/unified/sponsors/badge.svg [badge-funding-url]: https://opencollective.com/unified [badge-size-image]: https://img.shields.io/bundlejs/size/remark-lint-no-tabs [badge-size-url]: https://bundlejs.com/?q=remark-lint-no-tabs [esm-sh]: https://esm.sh [file-license]: https://github.com/remarkjs/remark-lint/blob/main/license [github-dotfiles-coc]: https://github.com/remarkjs/.github/blob/main/code-of-conduct.md [github-dotfiles-contributing]: https://github.com/remarkjs/.github/blob/main/contributing.md [github-dotfiles-health]: https://github.com/remarkjs/.github [github-dotfiles-support]: https://github.com/remarkjs/.github/blob/main/support.md [github-gist-esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c [github-remark-lint]: https://github.com/remarkjs/remark-lint [github-unified-transformer]: https://github.com/unifiedjs/unified#transformer [npm-install]: https://docs.npmjs.com/cli/install [typescript]: https://www.typescriptlang.org