LINT.md

LINT.md

This is a document to aid in linting of the project.

Running the linter

Basic lint commands

npm run lint

Rules

The configuration for eslint is to use the "recommended" set. You can review the recommended rules here: http://eslint.org/docs/rules/

This section notes the variation(s) from the "eslint:recommended" rules.

General Rules

no-unused-vars

Its an error to have unused variables, but okay to have unused paramaters, so functions can demonstrate their interface even if its not currently used.

"no-unused-vars": ["error", {"args": "none"}]

React-specific Rules

We do currently define two rules that are enforced via the React plugin for ESLint, eslint-plugin-react.

react/jsx-uses-vars

This rule is necessary to allow variables in jsx.

import ReactComponent from '...'
...
    <ReactComponent ... />
...

It's not so much a rule as a feature.

"react/jsx-uses-vars": "error"

react/jsx-uses-react

This rule is more nuanced, and caters to a specific instance: A file contains only jsx and a necessary React import. The file does not otherwise mention React, eslint thinks React is an unused var. This option stifles the unused var error. Note: "jsx-uses-react" is only effective with "no-unused-vars"

"react/jsx-uses-react": "error"

Toward a "React" recommended

We are currently working to adopt a recommended set of rules for the React plugin, as well.

Documentation

• eslint
• eslint-plugin-react

Advanced linting

This is a quick way to get the eslint command

npm i -g npm-run
alias eslint=npm-run eslint

Run the linter only on files changed in a feature branch

TRUNC=master
FEATURE="$(git rev-parse --abbrev-ref HEAD)"
FILES=$(git diff $TRUNC..$FEATURE --name-only | grep 'troposphere/static/js.*js$')

# You'll probably want to pass options to eslint (see package.json "lint")
eslint $FILES

Run a subset of rules over the codebase

RULES='{ "no-undef": "error" }'
eslint --env es6 --ext .js,.jsx --env browser --env commonjs --parser "babel-eslint" --rule "$RULES" --no-eslintrc troposphere/static/js

Note: eslint will always use the .eslintrc despite the use of the -c flag. The --no-eslintrc option will disable this. To be sure which rules are being included use --print-config.