Migrate jest-get-type to TypeScript (#7818)

Author: SimenB

CHANGELOG.md

@@ -9,6 +9,7 @@
 - `[*]`: Setup building, linting and testing of TypeScript ([#7808](https://github.com/facebook/jest/pull/7808))
 - `[pretty-format]`: Migrate to TypeScript ([#7809](https://github.com/facebook/jest/pull/7809))
 - `[diff-sequences]`: Migrate to Typescript ([#7820](https://github.com/facebook/jest/pull/7820))
+- `[jest-get-type]`: Migrate to TypeScript ([#7818](https://github.com/facebook/jest/pull/7818))
 
 ### Performance
 

packages/jest-get-type/package.json

@@ -12,5 +12,6 @@
   },
   "license": "MIT",
   "main": "build/index.js",
+  "types": "build/index.d.ts",
   "gitHead": "634e5a54f46b2a62d1dc81a170562e6f4e55ad60"
 }

packages/jest-get-type/src/__tests__/index.test.js renamed to packages/jest-get-type/src/__tests__/index.test.ts

@@ -6,9 +6,7 @@
  *
  */
 
-'use strict';
-
-const getType = require('..');
+import getType from '..';
 
 describe('.getType()', () => {
   test('null', () => expect(getType(null)).toBe('null'));

packages/jest-get-type/src/index.js renamed to packages/jest-get-type/src/index.ts

@@ -3,13 +3,9 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-'use strict';
-
-export type ValueType =
+type ValueType =
   | 'array'
   | 'boolean'
   | 'function'
@@ -26,7 +22,7 @@ export type ValueType =
 
 // get the type of a value with handling the edge cases like `typeof []`
 // and `typeof null`
-const getType = (value: any): ValueType => {
+const getType = (value: unknown): ValueType => {
   if (value === undefined) {
     return 'undefined';
   } else if (value === null) {
@@ -42,22 +38,23 @@ const getType = (value: any): ValueType => {
   } else if (typeof value === 'string') {
     return 'string';
   } else if (typeof value === 'object') {
-    if (value.constructor === RegExp) {
-      return 'regexp';
-    } else if (value.constructor === Map) {
-      return 'map';
-    } else if (value.constructor === Set) {
-      return 'set';
-    } else if (value.constructor === Date) {
-      return 'date';
+    if (value != null) {
+      if (value.constructor === RegExp) {
+        return 'regexp';
+      } else if (value.constructor === Map) {
+        return 'map';
+      } else if (value.constructor === Set) {
+        return 'set';
+      } else if (value.constructor === Date) {
+        return 'date';
+      }
     }
     return 'object';
-    // $FlowFixMe https://github.com/facebook/flow/issues/1015
   } else if (typeof value === 'symbol') {
     return 'symbol';
   }
 
   throw new Error(`value of unknown type: ${value}`);
 };
 
-module.exports = getType;
+export = getType;

packages/jest-get-type/tsconfig.json

@@ -0,0 +1,7 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "build"
+  }
+}