.eslintrc

{
    "extends": ["react-app"],
    "plugins": ["react"],
    "rules": {
        "quotes": ["error", "double"],                  // Use double-quotes for strings.
        "jsx-quotes": ["error", "prefer-double"],       // Use double-quotes for strings in JSX.
        "semi": ["error", "always"],                    // Enforce semicolon at the end of statements.
        "indent": ["error", 4, { "SwitchCase": 1 }],    // Indent with 4 spaces.
        "react/jsx-indent": ["error", 4],               // Indent JSX with 4 spaces.
        "no-multi-spaces": "error",                     // Do not allow multiple spaces in js.
        "no-multiple-empty-lines": ["error", { "max": 1 }], // Do not allow consecutive empty lines.
        "no-trailing-spaces": "error",                  // Disallow trailing whitespace at the end of lines.
        "max-len": ["error", { "code": 120 }],          // Restrict maximum line length to 120 characters.
        "no-console": "warn",                           // Restrict usage of console.log/error etc.
        "no-unused-vars": "error",                      // Do not allow declaring unused variables.
        "prefer-template": "error",                     // Use back-tick for string concatanation if needed.
        "object-curly-spacing": ["error", "always"],    // Enforce spaces inside inline object curly braces.
        "newline-before-return": "error",               // Enforce new-line before return statements.
        "react/jsx-curly-spacing": [2, {"when": "always",   // Enforce spaces inside objects in JSX.
            "spacing": {
                "objectLiterals": "never"
            },
            "children": true
        }],
        "react/jsx-tag-spacing": ["error", {            // Enforce space before tag close in JSX.
            "closingSlash": "never",
            "beforeSelfClosing": "always",
            "afterOpening": "never",
            "beforeClosing": "never"
        }],

        // Doc-block settings
        "require-jsdoc": ["error", {
            "require": {
                "FunctionDeclaration": true,
                "MethodDefinition": true,
                "ClassDeclaration": true,
                "ArrowFunctionExpression": true,
                "FunctionExpression": true
            }
        }],
        "valid-jsdoc": ["error", {
            "prefer": {
                "arg": "param",
                "argument": "param",
                "class": "constructor",
                "return": "returns",
                "virtual": "abstract"
            },
            "preferType": {
                "Boolean": "boolean",
                "Number": "number",
                "object": "Object",
                "String": "string"
            },
            "requireReturn": false,
            "requireReturnType": true,
            "requireParamDescription": false,
            "requireReturnDescription": false
        }],

        // React-specific settings
        "react/forbid-component-props": ["error", { "forbid": ["style"] }], // Forbid inline style in JSX.

        // Flow-specific settings
        "flowtype/newline-after-flow-annotation": [2, "never"],     // Do not allow empty line after flow annotation.
        "flowtype/require-valid-file-annotation": [2, "always"],    // Validate flow annotations and report missing ones.

        /* the following are to suppress some warnings that might come up due to eslint version inconsistency */
        "jsx-a11y/href-no-hash": "off",
        "jsx-a11y/anchor-is-valid": ["warn", { "aspects": ["invalidHref"] }],
        "jsx-a11y/anchor-has-content": "off"
    }
}