feat(join): Add join function (#423)

* feat: add join function

* fix: update testcase

benchmarks/performance/join.bench.ts

@@ -0,0 +1,13 @@
+import { bench, describe } from 'vitest';
+import { join as joinToolkit } from 'es-toolkit';
+import { join as joinLodash } from 'lodash';
+
+describe('join', () => {
+  bench('es-toolkit', () => {
+    joinToolkit([1, 2, 3], ',');
+  });
+
+  bench('lodash', () => {
+    joinLodash([1, 2, 3], ',');
+  });
+});

src/array/index.ts

@@ -18,6 +18,7 @@ export { groupBy } from './groupBy.ts';
 export { intersection } from './intersection.ts';
 export { intersectionBy } from './intersectionBy.ts';
 export { intersectionWith } from './intersectionWith.ts';
+export { join } from './join.ts';
 export { keyBy } from './keyBy.ts';
 export { maxBy } from './maxBy.ts';
 export { minBy } from './minBy.ts';

src/array/join.spec.ts

@@ -0,0 +1,16 @@
+import { describe, expect, it } from 'vitest';
+import { join } from './join.js';
+
+describe('join', () => {
+  it('should join elements of an array into a string', () => {
+    const arr = ['a', 'b', 'c'];
+    const result = join(arr);
+    expect(result).toBe('a,b,c');
+  });
+
+  it('should join elements of an array into a string with a custom separator', () => {
+    const arr = ['a', 'b', 'c'];
+    const result = join(arr, '~');
+    expect(result).toBe('a~b~c');
+  });
+});

src/array/join.ts

@@ -0,0 +1,20 @@
+/**
+ *
+ * Join elements of an array into a string.
+ *
+ * @template T - The type of elements in the array.
+ * @param {readonly T[]} array - The array to join.
+ * @param {string} separator - The separator used to join the elements, default is common separator `,`.
+ * @returns {string} - Returns a string containing all elements of the array joined by the specified separator.
+ *
+ * @example
+ * ```typescript
+ * const arr = ["a","b","c"];
+ * const result = join(arr, "~");
+ * console.log(result); // Output: "a~b~c"
+ * ```
+ *
+ */
+export function join<T>(array: readonly T[], separator = ','): string {
+  return array.join(separator);
+}