Ideas

🚧 Do you want to request a feature? Please review the list below and open an issue.

Inspiration

Here are tools that this linter could learn from. Suggestions welcome.

Linting rules

• https://github.com/yannickcr/eslint-plugin-react, last reviewed 2020-04-16
• https://github.com/vuejs/eslint-plugin-vue, last reviewed 2020-04-16
• https://github.com/htmlhint/HTMLHint, last reviewed 2020-04-16

Accessibility checks

• https://github.com/evcohen/eslint-plugin-jsx-a11y, last reviewed 2020-04-16
• https://github.com/squizlabs/HTML_CodeSniffer
• https://github.com/dequelabs/axe-core
• https://github.com/GoogleChrome/accessibility-developer-tools

HTML validation

• Nu "vnu.jar" HTML5 validator https://github.com/validator/validator
• https://github.com/html5lib/html5lib-python
• https://github.com/html5lib/html5lib-tests

Developer tools

• https://github.com/prettier/prettier, last reviewed 2020-05-06
• https://github.com/eslint/eslint, last reviewed 2020-05-06
• https://github.com/stylelint/stylelint

Research

• https://www.w3.org/WAI/RD/2011/metrics/paper3/
• https://dl.acm.org/doi/10.1145/2461121.2461124

Python developer tools

Most of curlylint’s CLI is already based on that of black: include/excludes, config file, error, success, verbose output. It would be nice to learn from flake8’s plugin system, eventually.

• https://pypi.org/project/flake8/
• https://github.com/tommilligan/flake8-fixme
• https://github.com/PyCQA/flake8-bugbear
• https://github.com/psf/black, last reviewed 2020-05-06

CLI ideas

• Support configuration from setup.cfg.
• Support configuration from .editorconfig.
• Support using a file with ignore paths.
• Disable colored output.
• Cache results / only check changed files.

Linting ideas

• Support disabling rules via code comments.

Rules ideas

Wishlist

Code smells

• <input type="submit"> is banned. Use <button type="submit"> instead.
• <input type="button"> is banned. Use <button type="button"> instead.
• <button> elements must have a type attribute.
  • https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/button-has-type.md
• Duplicate attributes on the same element are disallowed.
  • https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/jsx-no-duplicate-props.md
  • https://eslint.vuejs.org/rules/no-duplicate-attributes.html
  • https://github.com/htmlhint/HTMLHint/wiki/attr-no-duplication
• id must be unique.
  • https://github.com/htmlhint/HTMLHint/wiki/id-unique
• Forbid specified attributes on specified elements.
  • https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/forbid-component-props.md
  • https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/forbid-dom-props.md
  • https://eslint.vuejs.org/rules/no-static-inline-styles.html
• Forbid speicified elements.
  • https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/forbid-elements.md
• Disallow common typos (e.g. tab-index instead of tabindex).
  • https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/no-typos.md
• Disallow unescaped HTML entities
  • https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/no-unescaped-entities.md
  • https://github.com/htmlhint/HTMLHint/wiki/spec-char-escape

HTML5

• type="text/javascript" is banned on <script> elements.
• Deprecated attributes on an element are disallowed.
• Deprecated elements are disallowed.
• Elements can only have the attributes that are valid for them.
• Void elements have a consistent self-closing tag style.
  • https://github.com/htmlhint/HTMLHint/wiki/empty-tag-not-self-closed

Accessibility

• <img> tags must have an alt attribute.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/alt-text.md
  • https://github.com/htmlhint/HTMLHint/wiki/alt-require
• <a> tags must have textual content.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/anchor-has-content.md
• <a> tags cannot have content such as "Read more".
• <a> tags are only used for links.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/anchor-is-valid.md
• Alt text doesn’t start or end with "picture", "image", or "icon". Doesn’t end with a file extension.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/img-redundant-alt.md
• <table> elements must have a <caption>.
• Multiple heading elements cannot have the same content.
• Heading elements must have content.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/heading-has-content.md
• autocomplete attribute must use valid values.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/autocomplete-valid.md
• <html> element has a lang attribute.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/html-has-lang.md
• Enforce lang attribute has a valid value.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/lang.md
• Enforce iframe elements have a title attribute.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/iframe-has-title.md
• Enforce autofocus attribute is not used.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-autofocus.md
• tabindex should only be declared on interactive elements.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-noninteractive-tabindex.md
• Enforce tabindex value is not greater than zero.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/tabindex-no-positive.md

ARIA

• All ARIA roles must be valid.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/aria-role.md
• All ARIA attributes must be valid.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/aria-props.md
• Forbidden ARIA roles: menu, menubar, menuitem.
• Non-interactive elements should not be assigned interactive roles.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-noninteractive-element-to-interactive-role.md
• Enforce explicit role is not the same as implicit/default role property on element.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-redundant-roles.md
• Enforce that elements with ARIA roles must have all required attributes for that role.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/role-has-required-aria-props.md
• Enforce that elements with explicit or implicit roles defined contain only aria-* properties supported by that role.
  • https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/role-supports-aria-props.md

Security

• Enforce usage of rel="noopener noreferrer" for target="\_blank" <a> tags
  • https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/jsx-no-target-blank.md
• Enforce methods always having an explicit method to avoid unintentional data leaks in logs.
• Forbid the use of javascript: URLs
  • https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/jsx-no-script-url.md
  • https://github.com/htmlhint/HTMLHint/wiki/inline-script-disabled
• Forbid the use of inline script tags without CSP-compatible fingerprints.
• Forbid the use of inline styles without CSP-compatible fingerprints.
• Forbid loading scripts / styles from third-party resources, even with integrity attributes.
• Forbid the use of http: URLs
• Forbid the use of protocol-relative URLs //

Template languages

• Forbid specified template language syntax.

Django

• {% if foo %}{{ foo }}{% else %}bar{% endif %} => {{ foo|default:"bar" }}
• {% with foo as bar %} ... [ not using {{ bar }} ] ... {% endwith %}
• {% endblock %} vs. {% endblock blockname %}
• Forbid marking variables as "safe"

Code style

• Enforce ordering of HTML attributes
  • https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/jsx-sort-props.md
  • https://eslint.vuejs.org/rules/attributes-order.html
• Enforce compliance with .editorconfig

Rejected ideas

Formatting

See https://github.com/prettier/prettier/issues/5944#issuecomment-549805364. I’m much more interested in having automated formatting with a Prettier plugin, than adding formatting rules to a linter.