compact

🔸 題目描述

請實作一個 compact 效用函式。 compact 能將輸入的陣列中的 false、null、0、空字串、undefined 和 NaN 都去除，並輸出一個新的陣列。請實作此 compact 函式。

// 範例一
compact([0, 1, false, 2, "", 3, "hello"]);
// => [1, 2, 3, 'hello']

// 範例二
compact([null, undefined, NaN, " "]);
// =>[' ']

// 範例三
compact([{ name: "Alice" }, null, { age: 30 }, undefined]);
// =>[{ name: 'Alice' }, { age: 30 }]

Tests

test.ts

import { describe, expect, test } from "@jest/globals";
import compact from "./compact";

describe("compact", () => {
  test("removes all falsy values from the array", () => {
    expect(compact([0, 1, false, 2, "", 3, "hello"])).toEqual([
      1,
      2,
      3,
      "hello",
    ]);
    expect(compact([null, undefined, NaN, " "])).toEqual([" "]);
    expect(compact([{ name: "Alice" }, null, { age: 30 }, undefined])).toEqual([
      { name: "Alice" },
      { age: 30 },
    ]);
  });

  test("does not remove non-falsy values", () => {
    expect(compact([1, 2, 3])).toEqual([1, 2, 3]);
    expect(compact(["hello", "world"])).toEqual(["hello", "world"]);
    expect(compact([{ name: "Alice" }, { age: 30 }])).toEqual([
      { name: "Alice" },
      { age: 30 },
    ]);
  });
});

Solutions

解法一

solution1.ts

const compact = <T>(arr: T[]): T[] => {
    return arr.filter(Boolean);
    //false、null、0、空字串、undefined 和 NaN 都是 falsy value
};
export default compact;

解法二

solution2.ts

function compact(array: T[]) : T[] {
const result = []
for (const value of array) {
    if (value) {
    result.push(value)
    }
}
return result
}
export default compact;