eslint

.eslintrc

{
    "parserOptions": {
        // "sourceType": "module", // script by default
        "ecmaFeatures": {
            "impliedStrict": true
        }
    },
        "env": {
        "browser": true,
        "node": true,
        "mocha": true,
        "jasmine": true,
        "jquery": true,
        "serviceworker": true
    },
        "globals": {
        "var1": true,
        "var2": false
    },
    "rules": {
        "eqeqeq": 2, // or 1 for warn
        "curly": 2,
        "quotes": [2, "double"],
         "no-case-declarations": 2,
         "no-class-assign": 2,
         "no-cond-assign": 2,
         "no-console": 2,
         "no-const-assign": 2,
         "no-constant-condition": 2,
         "no-control-regex": 2,
         "no-debugger": 2,
         "no-delete-var": 2,
         "no-dupe-class-members": 2,
         "no-dupe-keys": 2,
         "no-dupe-args": 2,
         "no-duplicate-case": 2,
         "no-empty": 2,
         "no-empty-character-class": 2,
         "no-empty-pattern": 2,
         "no-ex-assign": 2,
         "no-extra-boolean-cast": 2,
         "no-extra-semi": 2,
         "no-fallthrough": 2,
         "no-func-assign": 2,
         "no-inner-declarations": 2,
         "no-invalid-regexp": 2,
         "no-irregular-whitespace": 2,
         "no-mixed-spaces-and-tabs": 2,
         "no-negated-in-lhs": 2,
         "no-new-symbol": 2,
         "no-obj-calls": 2,
         "no-octal": 2,
         "no-redeclare": 2,
         "no-regex-spaces": 2,
         "no-self-assign": 2,
         "no-sparse-arrays": 2,
         "no-this-before-super": 2,
         "no-undef": 2,
         "no-unexpected-multiline": 2,
         "no-unreachable": 2,
         "no-unused-labels": 2,
         "no-unused-vars": 2,
         "comma-dangle": 2,
         "constructor-super": 2,
         "use-isnan": 2,
         "valid-typeof": 2
    }
}