Add valid-typeof rule with support for BigInt

README.md

@@ -33,7 +33,8 @@ original ones as well!).
     "babel/object-curly-spacing": 1,
     "babel/quotes": 1,
     "babel/semi": 1,
-    "babel/no-unused-expressions": 1
+    "babel/no-unused-expressions": 1,
+    "babel/valid-typeof": 1
   }
 }
 ```
@@ -49,6 +50,7 @@ Each rule corresponds to a core `eslint` rule, and has the same options.
 - `babel/quotes`: doesn't complain about JSX fragment shorthand syntax (`<>foo</>;`)
 - `babel/semi`: doesn't fail when using `for await (let something of {})`. Includes class properties (🛠)
 - `babel/no-unused-expressions`: doesn't fail when using `do` expressions or [optional chaining](https://github.com/tc39/proposal-optional-chaining) (`a?.b()`).
+- `babel/valid-typeof`: doesn't complain when used with [BigInt](https://github.com/tc39/proposal-bigint) (`typeof BigInt(9007199254740991) === 'bigint'`).
 
 #### Deprecated
 

rules/valid-typeof.js

@@ -0,0 +1,12 @@
+"use strict";
+
+const ruleComposer = require('eslint-rule-composer');
+const eslint = require('eslint');
+const validTypeOf = new eslint.Linter().getRules().get('valid-typeof');
+
+module.exports = ruleComposer.filterReports(
+  validTypeOf,
+  (problem, metadata) => {
+    return problem.node.value !== 'bigint';
+  }
+)

tests/rules/valid-typeof.js

@@ -0,0 +1,193 @@
+/**
+ * @fileoverview Ensures that the results of typeof are compared against a valid string
+ * @author Ian Christian Myers
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const rule = require("../../rules/valid-typeof"),
+    RuleTester = require("../RuleTester");
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+const ruleTester = new RuleTester();
+
+ruleTester.run("valid-typeof", rule, {
+    valid: [
+        // Original test cases.
+        "typeof foo === 'string'",
+        "typeof foo === 'object'",
+        "typeof foo === 'function'",
+        "typeof foo === 'undefined'",
+        "typeof foo === 'boolean'",
+        "typeof foo === 'number'",
+        "'string' === typeof foo",
+        "'object' === typeof foo",
+        "'function' === typeof foo",
+        "'undefined' === typeof foo",
+        "'boolean' === typeof foo",
+        "'number' === typeof foo",
+        "typeof foo === typeof bar",
+        "typeof foo === baz",
+        "typeof foo !== someType",
+        "typeof bar != someType",
+        "someType === typeof bar",
+        "someType == typeof bar",
+        "typeof foo == 'string'",
+        "typeof(foo) === 'string'",
+        "typeof(foo) !== 'string'",
+        "typeof(foo) == 'string'",
+        "typeof(foo) != 'string'",
+        "var oddUse = typeof foo + 'thing'",
+        {
+            code: "typeof foo === 'number'",
+            options: [{ requireStringLiterals: true }]
+        },
+        {
+            code: "typeof foo === \"number\"",
+            options: [{ requireStringLiterals: true }]
+        },
+        {
+            code: "var baz = typeof foo + 'thing'",
+            options: [{ requireStringLiterals: true }]
+        },
+        {
+            code: "typeof foo === typeof bar",
+            options: [{ requireStringLiterals: true }]
+        },
+        {
+            code: "typeof foo === `string`",
+            options: [{ requireStringLiterals: true }],
+            parserOptions: { ecmaVersion: 6 }
+        },
+        {
+            code: "`object` === typeof foo",
+            options: [{ requireStringLiterals: true }],
+            parserOptions: { ecmaVersion: 6 }
+        },
+        {
+            code: "typeof foo === `str${somethingElse}`",
+            parserOptions: { ecmaVersion: 6 }
+        },
+
+        // Babel-specific test cases.
+        {
+          code: "typeof BigInt(Number.MAX_SAFE_INTEGER) === 'bigint'"
+        },
+        {
+          code: "'bigint' === typeof BigInt(Number.MAX_SAFE_INTEGER)"
+        },
+        {
+          code: "typeof BigInt(Number.MAX_SAFE_INTEGER) === 'bigint'",
+          options: [{ requireStringLiterals: true }]
+        },
+    ],
+    invalid: [
+        {
+          code: "typeof foo === 'strnig'",
+          errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "'strnig' === typeof foo",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "if (typeof bar === 'umdefined') {}",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "typeof foo !== 'strnig'",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "'strnig' !== typeof foo",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "if (typeof bar !== 'umdefined') {}",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "typeof foo != 'strnig'",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "'strnig' != typeof foo",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "if (typeof bar != 'umdefined') {}",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "typeof foo == 'strnig'",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "'strnig' == typeof foo",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "if (typeof bar == 'umdefined') {}",
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "if (typeof bar === `umdefined`) {}",
+            parserOptions: { ecmaVersion: 6 },
+            errors: [{ message: "Invalid typeof comparison value.", type: "TemplateLiteral" }]
+        },
+        {
+            code: "typeof foo == 'invalid string'",
+            options: [{ requireStringLiterals: true }],
+            errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+            code: "typeof foo == Object",
+            options: [{ requireStringLiterals: true }],
+            errors: [{ message: "Typeof comparisons should be to string literals.", type: "Identifier" }]
+        },
+        {
+            code: "typeof foo === undefined",
+            options: [{ requireStringLiterals: true }],
+            errors: [{ message: "Typeof comparisons should be to string literals.", type: "Identifier" }]
+        },
+        {
+            code: "undefined === typeof foo",
+            options: [{ requireStringLiterals: true }],
+            errors: [{ message: "Typeof comparisons should be to string literals.", type: "Identifier" }]
+        },
+        {
+            code: "undefined == typeof foo",
+            options: [{ requireStringLiterals: true }],
+            errors: [{ message: "Typeof comparisons should be to string literals.", type: "Identifier" }]
+        },
+        {
+            code: "typeof foo === `undefined${foo}`",
+            options: [{ requireStringLiterals: true }],
+            parserOptions: { ecmaVersion: 6 },
+            errors: [{ message: "Typeof comparisons should be to string literals.", type: "TemplateLiteral" }]
+        },
+        {
+            code: "typeof foo === `${string}`",
+            options: [{ requireStringLiterals: true }],
+            parserOptions: { ecmaVersion: 6 },
+            errors: [{ message: "Typeof comparisons should be to string literals.", type: "TemplateLiteral" }]
+        },
+
+        // Babel-specific test cases.
+        {
+          code: "typeof foo === 'bgiint'",
+          errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+        {
+          code: "'bignit' === typeof foo",
+          errors: [{ message: "Invalid typeof comparison value.", type: "Literal" }]
+        },
+    ]
+});