.eslintrc.json

{
	"root": true,
	"env": {
		"node": true,
		"es6": true
	},
	"plugins": ["prettier", "promise"],
	"extends": ["eslint:recommended", "plugin:prettier/recommended", "plugin:promise/recommended"],
	"rules": {
		// for prettier compat
		"implicit-arrow-linebreak": "off",

		"no-console": "error",
		"no-debugger": "error",
		"curly": ["error", "all"],
		"no-eval": ["error", {}],
		"no-multiple-empty-lines": ["error", { "max": 1, "maxBOF": 0 }],
		"no-var": "error",
		"no-dupe-keys": "error",
		"no-prototype-builtins": "error",
		"prefer-arrow-callback": "error",
		"eol-last": ["error", "always"],
		"eqeqeq": ["error", "always"],
		"no-unused-vars": "error",

		"@typescript-eslint/no-var-requires": "warn",

		"promise/prefer-await-to-then": "error"
	},
	"parserOptions": {
		"ecmaVersion": 2020,
		"sourceType": "module"
	},
	"overrides": [
		{
			"files": ["*.js"],
			"rules": {
				"@typescript-eslint/explicit-module-boundary-types": "off",
				"@typescript-eslint/no-var-requires": "off",
				"@typescript-eslint/no-unused-vars": "off"
			}
		},
		{
			"files": ["*.vue"],
			"parser": "vue-eslint-parser",
			"parserOptions": {
				"parser": "@typescript-eslint/parser",
				"ecmaVersion": 2020,
				"sourceType": "module"
			},
			"extends": ["plugin:vue/base", "plugin:vue/essential", "@vue/typescript/recommended"],
			"rules": {
				// HACK: this rule is required, otherwise travis-ci will fail (for some reason)
				// even through when run locally, no linting errors occur.
				"vue/no-parsing-error": [
					"error",
					{
						"invalid-first-character-of-tag-name": false
					}
				]
			}
		},
		{
			"files": ["*.ts", "*.tsx"],
			"parser": "@typescript-eslint/parser",
			"parserOptions": {
				"ecmaVersion": 2020,
				"sourceType": "module",
				"project": ["./tsconfig.json"]
			},
			"rules": {
				"no-unused-vars": "off",
				"@typescript-eslint/adjacent-overload-signatures": "error",
				"@typescript-eslint/switch-exhaustiveness-check": "error",
				"@typescript-eslint/restrict-template-expressions": "warn",
				"@typescript-eslint/no-unnecessary-type-assertion": "warn",
				"@typescript-eslint/no-unnecessary-boolean-literal-compare": "warn",

				"@typescript-eslint/no-unsafe-call": "off", // TODO: switch to warn
				"@typescript-eslint/no-unsafe-member-access": "off", // TODO: switch to warn
				"@typescript-eslint/no-unsafe-assignment": "off" // TODO: switch to warn
			}
		}
	]
}