.eslintrc

{
    "parser": "@babel/eslint-parser",
    "env": {
        "browser": true,
        "node": true,
        "es6": true
    },
    "extends": [
        "eslint:recommended",
        "plugin:react/recommended"
    ],
    "rules": {
        "no-console": "warn",
        "no-unused-vars": "warn",
        // semicolons
        "semi": "error",
        // dangling commas
        "comma-dangle": ["warn", "always-multiline"],
        // consistent newlines around array brackets
        "array-bracket-newline": ["warn", "consistent"],
        // no spaces around array brackets: [a]
        "array-bracket-spacing": ["warn", "never"],
        // pad same-line { ... } with whitespace
        "block-spacing": "warn",
        // if () {\n } else {\n }
        "brace-style": ["warn", "1tbs"],
        // no space before, space after
        "comma-spacing": "warn",
        // commas should be at the end of the current line
        "comma-style": "warn",
        // compute properties should look like indexing: [a]
        "computed-property-spacing": "warn",
        // no spaces after function names: something()
        "func-call-spacing": "warn",
        // consistent newlines around function arguments
        "function-paren-newline": ["warn", "consistent"],
        // indent with 4 spaces
        "indent": "warn",
        // prefer double quotes in JSX
        "jsx-quotes": "warn",
        // object key: spacing
        "key-spacing": "warn",
        // space before and after keywords
        "keyword-spacing": "warn",
        // use \n for line breaks
        "linebreak-style": "warn",
        // one statement per line
        "max-statements-per-line": "warn",
        // disallow `new Object;`
        "new-parens": "warn",
        // disallow if as the only statement inside else
        "no-lonely-if": "warn",
        // disallow trailing spaces
        "no-trailing-spaces": "warn",
        // disallow whitespace before the property dot
        "no-whitespace-before-property": "warn",
        // consistent newlines around object constructors
        "object-curly-newline": "warn",
        // operators on the next line
        "operator-linebreak": ["warn", "before", { "overrides": { "=": "after" } }],
        // no line padding inside { ... }
        "padded-blocks": ["warn", "never"],
        // prefer single quotes
        "quotes": ["warn", "single", { "avoidEscape": true, "allowTemplateLiterals": true }],
        // no spaces before semicolons
        "semi-spacing": "warn",
        // semicolons are at the end
        "semi-style": "warn",
        // blocks need a preceding space (e.g. in if (a) { ... } after the condition)
        "space-before-blocks": "warn",
        // function definition parens have a space before
        "space-before-function-paren": "warn",
        // no spaces in parentheses
        "space-in-parens": "warn",
        // spaces around operators
        "space-infix-ops": "warn",
        // spaces after word operators (like new)
        "space-unary-ops": "warn",
        // colon spacing for switch cases
        "switch-colon-spacing": "warn",
        // no space after the template string tag
        "template-tag-spacing": "warn",
        // spaces around the =>
        "arrow-spacing": "warn",
        // function* name for generator functions
        "generator-star-spacing": ["warn", "after"],
        // use let or const
        "no-var": "warn",
        // prefer immutability
        "prefer-const": "warn",
        // don’t use `arguments`
        "prefer-rest-params": "error",
        // no spaces after the ... operator
        "rest-spread-spacing": "warn",
        // no spaces in the template string ${expression}
        "template-curly-spacing": "warn",
        // yield* value
        "yield-star-spacing": "warn",
        // allow `class` and `for` (for preact)
        "react/no-unknown-property": ["error", {
            "ignore": ["class", "for"]
        }],
        // preact doesn’t care
        "react/prop-types": "off",
        // preact doesn’t care
        "react/display-name": "off",
    },
    "settings": {
        "react": {
            "version": "16",
            "pragma": "h",
        }
    }
}