.eslintrc.json

{
  "root": true,
  "ignorePatterns": ["**/*"],
  "plugins": ["@nx"],
  "parserOptions": {
    "ecmaVersion": 2020,
    "sourceType": "module",
    "ecmaFeatures": {}
  },

  // === General rules =========================================================

  "rules": {
    // Omitted semicolons are hugely popular, yet within the compiler it makes
    // sense to be better safe than sorry.
    "semi": "error",

    // Our code bases uses 2 spaces for indentation, and we enforce it here so
    // files don't mix spaces, tabs or different indentation levels.
    "indent": [
      "error",
      2,
      {
        "SwitchCase": 1,
        "VariableDeclarator": "first",
        "offsetTernaryExpressions": true,
        "ignoredNodes": [
          // FIXME: something's odd here
          "ConditionalExpression > *",
          "ConditionalExpression > * > *",
          "ConditionalExpression > * > * > *"
        ]
      }
    ],

    // This is mostly visual style, making comments look uniform.
    "spaced-comment": [
      "error",
      "always",
      {
        "markers": ["/"], // triple-slash
        "exceptions": ["/"] // all slashes
      }
    ],

    // This tends to be annoying as it encourages developers to make everything
    // that is never reassigned a 'const', sometimes semantically incorrect so,
    // typically leading to huge diffs in follow-up PRs modifying affected code.
    "prefer-const": "off",

    // It is perfectly fine to declare top-level variables with `var`, yet this
    // rule doesn't provide configuration options that would help.
    "no-var": "off",

    // Quite often, dealing with multiple related cases at once or otherwise
    // falling through is exactly the point of using a switch.
    "no-fallthrough": "off",

    // Typical false-positives here are `do { ... } while (true)` statements or
    // similar, but the only option provided here is not checking any loops.
    "no-constant-condition": ["error", { "checkLoops": false }],

    // Functions are nested in blocks occasionally, and there haven't been any
    // problems with this so far, so turning the check off.
    "no-inner-declarations": "off",

    // Quite common in scenarios where an iteration starts at `current = this`.
    "@typescript-eslint/no-this-alias": "off",

    // Disabled here, but enabled again for JavaScript files.
    "no-unused-vars": "off",

    // Disabled here, but enabled again for TypeScript files.
    "@typescript-eslint/no-unused-vars": "off"
  },
  "overrides": [
    {
      "files": ["*.ts", "*.tsx", "*.js", "*.jsx"],
      "rules": {
        "@nx/enforce-module-boundaries": [
          "error",
          {
            "enforceBuildableLibDependency": true,
            "allow": [],
            "depConstraints": [
              {
                "sourceTag": "*",
                "onlyDependOnLibsWithTags": ["*"]
              }
            ]
          }
        ]
      }
    },
    {
      "files": ["*.ts", "*.tsx"],
      "extends": ["plugin:@nx/typescript"],
      "rules": {}
    },
    {
      "files": ["*.js", "*.jsx"],
      "extends": ["plugin:@nx/javascript"],
      "rules": {}
    },
    {
      "files": ["*.spec.ts", "*.spec.tsx", "*.spec.js", "*.spec.jsx"],
      "env": {
        "jest": true
      },
      "rules": {}
    },

    // === TypeScript rules ====================================================

    {
      "files": ["**/assembly/**/*.ts"],
      "rules": {
        // Enforcing to remove function parameters on stubs makes code less
        // maintainable, so we instead allow unused function parameters.
        "@typescript-eslint/no-unused-vars": [
          "warn",
          {
            "vars": "local",
            "varsIgnorePattern": "^_|^[A-Z](?:From|To)?$", // ignore type params
            "args": "none",
            "ignoreRestSiblings": false
          }
        ],

        // Namespaces are quite useful in AssemblyScript
        "@typescript-eslint/no-namespace": "off",

        // There is actually codegen difference here
        "@typescript-eslint/no-array-constructor": "off",

        // Sometimes it can't be avoided to add a @ts-ignore
        "@typescript-eslint/ban-ts-comment": "off",

        // Utilized to achieve portability in some cases
        "@typescript-eslint/no-non-null-assertion": "off"
      }
    },

    // === Compiler rules (extends AssemblyScript rules) =======================

    {
      "files": ["**/assembly/**/*.ts"],
      "rules": {
        // There is an actual codegen difference here - TODO: revisit
        "no-cond-assign": "off",

        // Not all types can be omitted in AS yet - TODO: revisit
        "@typescript-eslint/no-inferrable-types": "off",

        // Used rarely to reference internals that are not user-visible
        "@typescript-eslint/triple-slash-reference": "off",

        // The compiler has its own `Function` class for example
        "no-shadow-restricted-names": "off",
        "@typescript-eslint/ban-types": "off"
      }
    },

    // === Standard Library rules (extends AssemblyScript rules) ===============

    {
      "files": ["**/assembly/**/*.ts"],
      "rules": {
        // We are implementing with --noLib, so we shadow all the time
        "no-shadow-restricted-names": "off",

        // Similarly, sometimes we need the return type to be String, not string
        "@typescript-eslint/ban-types": "off"
      }
    },

    // === Standard Definition rules (extends TypeScript rules) ================

    {
      "files": ["**/assembly/**/*.d.ts"],
      "rules": {
        // Often required to achieve compatibility with TypeScript
        "@typescript-eslint/no-explicit-any": "off",

        // Interfaces can be stubs here, i.e. not yet fully implemented
        "@typescript-eslint/no-empty-interface": "off",

        // Definitions make use of `object` to model rather unusual constraints
        "@typescript-eslint/ban-types": "off"
      }
    },

    // === Test rules (extends TypeScript rules) ===============================

    {
      "files": ["**/assembly/__tests__/**/*.ts"],
      "rules": {
        // Tests typically include unusual code patterns on purpose. This is
        // very likely not an extensive list, but covers what's there so far.
        "no-empty": "off",
        "no-cond-assign": "off",
        "no-compare-neg-zero": "off",
        "no-inner-declarations": "off",
        "no-constant-condition": "off",
        "use-isnan": "off",
        "@typescript-eslint/no-namespace": "off",
        "@typescript-eslint/no-unused-vars": "off",
        "@typescript-eslint/no-empty-function": "off",
        "@typescript-eslint/no-non-null-assertion": "off",
        "@typescript-eslint/no-extra-semi": "off",
        "@typescript-eslint/no-inferrable-types": "off",
        "@typescript-eslint/ban-types": "off",
        "@typescript-eslint/triple-slash-reference": "off",
        "@typescript-eslint/ban-ts-comment": "off",
        "@typescript-eslint/no-extra-non-null-assertion": "off",
        "@typescript-eslint/no-empty-interface": "off"
      }
    }
  ]
}