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clamp

🔸 題目描述

你正在開發一個處理數值資料的系統。請寫一個名為 clamp 的函式，它需要三個參數：

  • 一個數值 number
  • 一個最小值 lower
  • 一個最大值 upper

此函式應確保輸出的 number 始終落在指定的範圍内，包括最小值和最大值本身。你會如何實作這個 clamp 呢?

// 在範圍中，返回原值
clamp(7, 0, 9); // => 7

// 小於 lower，返回 lower
clamp(-12, -4, 5); // => -4

// 大於 upper，返回 upper
clamp(18, 3, 9); // => 9

Tests​

test.ts
import { describe, expect, test } from "@jest/globals";
import clamp from "./clamp";
describe("clamp", () => {
  test("should return the input number when it is within the specified range", () => {
    expect(clamp(7, 0, 9)).toBe(7);
    expect(clamp(3, -5, 5)).toBe(3);
    expect(clamp(-2, -10, 10)).toBe(-2);
  });

  test("should return the lower bound when the input number is less than the lower bound", () => {
    expect(clamp(-5, 0, 9)).toBe(0);
    expect(clamp(-10, -5, 5)).toBe(-5);
    expect(clamp(-15, -10, 10)).toBe(-10);
  });

  test("should return the upper bound when the input number is greater than the upper bound", () => {
    expect(clamp(10, 0, 9)).toBe(9);
    expect(clamp(6, -5, 5)).toBe(5);
    expect(clamp(15, -10, 10)).toBe(10);
  });
});

Solutions​

solution1.js
function clamp(number: number, lower: number, upper: number) {
if (number < lower) {
    return lower;
} else if (number > upper) {
    return upper;
} else {
    return number;
}