Add getIn() method

Author: WezomDev

README.md

@@ -7,6 +7,6 @@
 
 ## Coverage
 
-| Statements | Branches | Functions | Lines |
-| --- | --- | --- | --- |
-| ![Statements](https://img.shields.io/badge/Coverage-100%25-brightgreen.svg) | ![Branches](https://img.shields.io/badge/Coverage-93.33%25-brightgreen.svg) | ![Functions](https://img.shields.io/badge/Coverage-100%25-brightgreen.svg) | ![Lines](https://img.shields.io/badge/Coverage-100%25-brightgreen.svg) |
+| Statements                                                                  | Branches                                                                    | Functions                                                                  | Lines                                                                  |
+| --------------------------------------------------------------------------- | --------------------------------------------------------------------------- | -------------------------------------------------------------------------- | ---------------------------------------------------------------------- |
+| ![Statements](https://img.shields.io/badge/Coverage-100%25-brightgreen.svg) | ![Branches](https://img.shields.io/badge/Coverage-95.24%25-brightgreen.svg) | ![Functions](https://img.shields.io/badge/Coverage-100%25-brightgreen.svg) | ![Lines](https://img.shields.io/badge/Coverage-100%25-brightgreen.svg) |

src/get-in.test.ts

@@ -0,0 +1,58 @@
+// -----------------------------------------------------------------------------
+// Deps
+// -----------------------------------------------------------------------------
+
+import { getIn } from './get-in';
+
+// -----------------------------------------------------------------------------
+// Tests
+// -----------------------------------------------------------------------------
+
+const testCases: {
+	parameters: Parameters<typeof getIn>;
+	result: ReturnType<typeof getIn>;
+}[] = [
+	{
+		parameters: [{ key: 'value' }, 'key'],
+		result: 'value'
+	},
+	{
+		parameters: [{ key: 'value' }, 'ZZZ'],
+		result: undefined
+	},
+	{
+		parameters: [
+			{
+				key1: {
+					key2: {
+						key3: 'value'
+					}
+				}
+			},
+			'key1.key2.key3'
+		],
+		result: 'value'
+	},
+	{
+		parameters: [
+			{
+				key1: ['value0', 'value1', 'value2']
+			},
+			'key1[1]'
+		],
+		result: 'value1'
+	},
+	{
+		parameters: [['value0', 'value1', 'value2'], '[1]'],
+		result: 'value1'
+	}
+];
+
+describe('getIn tool', () => {
+	testCases.forEach(({ parameters, result }, i) => {
+		test(`test #${i + 1}: ${parameters.join(', ')}`, () => {
+			const value = getIn(...parameters);
+			expect(value).toStrictEqual(result);
+		});
+	});
+});

src/get-in.ts

@@ -0,0 +1,37 @@
+// -----------------------------------------------------------------------------
+// Deps
+// -----------------------------------------------------------------------------
+
+import { IPlainObject } from './types';
+import { toPath } from './to-path';
+import { isPlainObject } from './is-plain-object';
+
+/**
+ * Convert string sample in to the path (array)
+ * Inspired by final-form's `toPath` helper
+ * {@link https://github.com/final-form/final-form/blob/master/src/structure/toPath.js}
+ * @param {IPlainObject|Array} sample
+ * @param {string} keyPath
+ */
+export function getIn<GValue = any>(
+	sample: IPlainObject | GValue[],
+	keyPath: string
+): GValue | undefined {
+	const path = toPath(keyPath);
+	const pathLength = path.length;
+
+	let current: any = sample;
+	for (let i = 0; i < pathLength; i++) {
+		const key: string = path[i];
+		if (
+			(isPlainObject(current) && current.hasOwnProperty(key)) ||
+			(Array.isArray(current) && !isNaN(+key))
+		) {
+			current = current[key];
+		} else {
+			current = undefined;
+			break;
+		}
+	}
+	return current;
+}

src/to-path.test.ts

@@ -2,7 +2,7 @@
 // Deps
 // -----------------------------------------------------------------------------
 
-import toPath from './to-path';
+import { toPath } from './to-path';
 
 // -----------------------------------------------------------------------------
 // Tests

src/to-path.ts

@@ -8,7 +8,7 @@ const regex = /(\[(?=\d+])|(?<=\[\d+)])|\.+/;
  * @param {string|null} [sample]
  * @returns {string[]}
  */
-export default (sample?: string | null): string[] => {
+export const toPath = (sample?: string | null): string[] => {
 	if (typeof sample === 'string' && sample.length > 0 && sample !== 'hasOwnProperty') {
 		if (!cache.hasOwnProperty(sample)) {
 			cache[sample] = sample