Merge pull request #18 from ryoppippi/feature/17

 implement split function

Author: ryoppippi

src/index.js

@@ -4,3 +4,4 @@ export * from './capitalize.js';
 export * from './uncapitalize.js';
 export * from './lowercase.js';
 export * from './uppercase.js';
+export * from './split.js';

src/split.js

@@ -0,0 +1,37 @@
+// @ts-strict
+
+/**
+ * @template {Readonly<string>} T
+ * @template {Readonly<string>} U
+ * @typedef {import('type-fest').IsStringLiteral<T> extends true ? import('type-fest').Split<T,U> : string[]} SplitString<T,U>
+ */
+
+/**
+ * @description Split string by separator
+ *
+ * @template {Readonly<string>} T
+ *
+ * @template {Readonly<string>} U
+ *
+ * @param {T} input - string to split. type should be matched to T
+ *
+ * @param {U} separator - separator to split string. type should be matched to U
+ *
+ * @returns {SplitString<T,U>}
+ *
+ * @example
+ * split('Abc', 'b') // returns ['A', 'c']
+ *
+ * @example
+ * split('a-b-c', '-') // returns ['a', 'b', 'c']
+ *
+ * @example
+ * split('a-b-c', '') // returns ['a', '-', 'b', '-', 'c']
+ *
+ * @example
+ * split('a-b-c', '$') // returns ['a-b-c']
+ *
+ */
+export function split(input, separator) {
+	return /** @type {SplitString<T,U>} */ input.split(separator);
+}

src/split.test.ts

@@ -0,0 +1,28 @@
+import { split } from '.';
+import { describe, it, expect } from 'vitest';
+describe('split', () => {
+	it('should split a string into an array', () => {
+		const before = 'abc' as const;
+		const splitted = split(before, '');
+		const expected = ['a', 'b', 'c'] satisfies typeof splitted;
+		expect(splitted).toEqual(expected);
+	});
+	it('should split a string into an array', () => {
+		const before = 'a-b-c' as const;
+		const splitted = split(before, '-');
+		const expected = ['a', 'b', 'c'] satisfies typeof splitted;
+		expect(splitted).toEqual(expected);
+	});
+	it('should split a string into an array', () => {
+		const before = 'a-b-c' as const;
+		const splitted = split(before, '');
+		const expected = ['a', '-', 'b', '-', 'c'] satisfies typeof splitted;
+		expect(splitted).toEqual(expected);
+	});
+	it('should not split a string into an array with wrong separator', () => {
+		const before = 'a-b-c' as const;
+		const splitted = split(before, '$');
+		const expected = ['a-b-c'] satisfies typeof splitted;
+		expect(splitted).toEqual(expected);
+	});
+});