.eslintrc.json

{
    "rules": {
        "curly": ["error"],
        "eol-last": ["error"],
        // Blockly/Google use 2-space indents.
        // Blockly/Google uses +4 space indents for line continuations.
        // Ignore default rules for ternary expressions.
        "indent": [
            "error", 2,
            {
                "SwitchCase": 1,
                "MemberExpression": 2,
                "ObjectExpression": 1,
                "FunctionDeclaration": {
                    "body": 1,
                    "parameters": 2
                },
                "FunctionExpression": {
                    "body": 1,
                    "parameters": 2
                },
                "CallExpression": {
                    "arguments": 2
                },
                "ignoredNodes": ["ConditionalExpression"]
            }
        ],
        "keyword-spacing": ["error"],
        "linebreak-style": ["error", "unix"],
        "max-len": [
            "error",
            {
                "code": 100,
                "tabWidth": 4,
                "ignoreStrings": true,
                "ignoreRegExpLiterals": true,
                "ignoreUrls": true
            }
        ],
        "no-trailing-spaces": ["error", { "skipBlankLines": true }],
        "no-unused-vars": [
            "error",
            {
                "args": "after-used",
                // Ignore vars starting with an underscore.
                "varsIgnorePattern": "^_",
                // Ignore arguments starting with an underscore.
                "argsIgnorePattern": "^_"
            }
        ],
        "no-use-before-define": ["error"],
        // Blockly uses for exporting symbols. no-self-assign added in eslint 5.
        "no-self-assign": ["off"],
        // Blockly uses single quotes except for JSON blobs, which must use double quotes.
        "quotes": ["off"],
        "semi": ["error", "always"],
        // Blockly doesn't have space before function paren when defining functions.
        "space-before-function-paren": ["error", "never"],
        // Blockly doesn't have space before function paren when calling functions.
        "func-call-spacing": ["error", "never"],
        "space-infix-ops": ["error"],
        // Blockly uses 'use strict' in files.
        "strict": ["off"],
        // Closure style allows redeclarations.
        "no-redeclare": ["off"],
        "valid-jsdoc": ["error", {"requireReturn": false}],
        "no-console": ["off"],
        "no-multi-spaces": ["error", { "ignoreEOLComments": true }],
        "operator-linebreak": ["error", "after"],
        "spaced-comment": ["error", "always", {
            "block": {
                "balanced": true
            },
            "exceptions": ["*"]
        }],
        "es5/no-es6-methods": ["warn"]
    },
    "env": {
        "browser": true
    },
    "globals": {
        "Blockly": true,
        "goog": true
    },
    "extends": [
        "eslint:recommended",
        "plugin:es5/no-es2015"
    ]
}