.eslintrc.json

{
    "rules": {
        "curly": ["error"],
        "eol-last": ["error"],
        "_comment": "Blockly/Google use 2-space indents",
        "_comment": "Blockly/Google uses +4 space indents for line continuations.",
        "_comment": "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",
                "_comment": "Ignore vars starting with an underscore.",
                "varsIgnorePattern": "^_",
                "_comment": "Ignore arguments starting with an underscore.",
                "argsIgnorePattern": "^_"
            }
        ],
        "no-use-before-define": ["error"],
        "_comment":"Blockly uses for exporting symbols. no-self-assign added in eslint 5.",
        "no-self-assign": ["off"],
        "_comment": "Blockly uses single quotes except for JSON blobs, which must use double quotes.",
        "quotes": ["off"],
        "semi": ["error", "always"],
        "_comment": "Blockly doesn't have space before function paren when defining functions",
        "space-before-function-paren": ["error", "never"],
        "_comment": "Blocklydoesn't have space before function paren when calling functions",
        "func-call-spacing": ["error", "never"],
        "space-infix-ops": ["error"],
        "_comment": "Blockly uses 'use strict' in files",
        "strict": ["off"],
        "_comment": "Blockly often uses cond-assignment in loops",
        "no-cond-assign": ["off"],
        "_comment": "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": ["*"]
        }]
    },
    "env": {
        "browser": true
    },
    "globals": {
        "Blockly": true,
        "goog": true
    },
    "extends": "eslint:recommended"
}