feat: expose isPlainObject util (#92)

Author: P0lip

src/__tests__/_utils.spec.ts

@@ -0,0 +1,13 @@
+import { isPlainObject } from '../isPlainObject';
+
+it('isPlainObject', () => {
+  expect(isPlainObject(new class Foo {}())).toBe(false);
+  expect(isPlainObject([1, 2, 3])).toBe(false);
+
+  expect(isPlainObject({ x: 0, y: 0 })).toBe(true);
+  expect(isPlainObject(Object.create(null))).toBe(true);
+
+  const a = new class {}();
+  a.constructor = Object;
+  expect(isPlainObject(a)).toBe(true);
+});

src/__tests__/isPlainObject.spec.ts

@@ -26,18 +26,3 @@ export const replaceInString = (str: string, find: string, repl: string): string
 
   return res;
 };
-
-export function isPlainObject(maybeObj: unknown): maybeObj is { [key in PropertyKey]: unknown } {
-  if (typeof maybeObj !== 'object' || maybeObj === null) {
-    return false;
-  }
-
-  const proto = Object.getPrototypeOf(maybeObj);
-  return (
-    proto === null ||
-    proto === Object.prototype ||
-    // this is to be more compatible with Lodash.isPlainObject that also checks the constructor
-    (typeof maybeObj.constructor === 'function' &&
-      Function.toString.call(Object) === Function.toString.call(maybeObj.constructor))
-  );
-}

src/_utils.ts

@@ -1,4 +1,4 @@
-import { isPlainObject } from './_utils';
+import { isPlainObject } from './isPlainObject';
 import { pathToPointer } from './pathToPointer';
 
 export const decycle = (obj: unknown, replacer?: (value: any) => any) => {

src/decycle.ts

@@ -12,6 +12,7 @@ export * from './getLastPathSegment';
 export * from './getLocationForJsonPath';
 export * from './hasRef';
 export * from './isLocalRef';
+export * from './isPlainObject';
 export * from './parseWithPointers';
 export * from './pathToPointer';
 export * from './pointerToPath';

src/index.ts

@@ -0,0 +1,14 @@
+export function isPlainObject(maybeObj: unknown): maybeObj is Record<PropertyKey, unknown> {
+  if (typeof maybeObj !== 'object' || maybeObj === null) {
+    return false;
+  }
+
+  const proto = Object.getPrototypeOf(maybeObj);
+  return (
+    proto === null ||
+    proto === Object.prototype ||
+    // this is to be more compatible with Lodash.isPlainObject that also checks the constructor
+    (typeof maybeObj.constructor === 'function' &&
+      Function.toString.call(Object) === Function.toString.call(maybeObj.constructor))
+  );
+}

src/isPlainObject.ts

@@ -1,6 +1,6 @@
 import { Dictionary } from '@stoplight/types';
-import { isPlainObject } from './_utils';
 import { extractSourceFromRef } from './extractSourceFromRef';
+import { isPlainObject } from './isPlainObject';
 import { pointerToPath } from './pointerToPath';
 
 function _resolveInlineRef(document: Dictionary<unknown>, ref: string, seen: unknown[]): unknown {