✨ Filter

Author: UltiRequiem

src/language/filter.test.ts

@@ -0,0 +1,7 @@
+import { filter } from "./filter.ts";
+import { assertEquals } from "../../deps.ts";
+
+Deno.test("filter", () => {
+  const data = filter([1, 2, 3, 4, 5], (item) => item % 2 === 0);
+  assertEquals(data, [2, 4]);
+});

src/language/filter.ts

@@ -0,0 +1,17 @@
+export type FilterCallback<T> = (
+  item: T,
+  index: number,
+  array: readonly T[],
+) => boolean;
+
+export function filter<T>(array: readonly T[], test: FilterCallback<T>) {
+  const result: T[] = [];
+
+  for (const [index, value] of array.entries()) {
+    if (test(value, index, array)) {
+      result.push(value);
+    }
+  }
+
+  return result;
+}