重构 JavaScript (Swtich & Function)答案

【问题标题】：Refactoring JavaScript (Swtich & Function)重构 JavaScript (Swtich & Function)
【发布时间】：2022-11-01 12:28:16
【问题描述】：

我是编码的初学者，我正在学习JS。我想知道如何在下面的代码中的开关内编写一个函数（如果可能的话），将代码变小。

我试图将每个操作的功能放在开关内，但它从来没有奏效。帮助我改进我的代码。谢谢！

//Calculator of Basic Operations

function addition(a, b) {
  return (a + b);
}

function subtraction(a, b) {
  return (a - b);
}

function multiplication(a, b) {
  return (a * b);
}

function division(a, b) {
  return (a / b);
}

console.log('Choose the number for the operation you want to use.');
console.log('1 - Addition');
console.log('2 - Subtraction');
console.log('3 - Multiplication');
console.log('4 - Division');

let calcAB = prompt('Operation: ');

switch (calcAB) {

  case '1':
    a = Number(prompt('Enter the value for A: '));
    b = Number(prompt('Enter the value for B: '));
    console.log(`The addition result is "${addition(a, b)}"`);
    break;

  case '2':
    a = Number(prompt('Enter the value for A: '));
    b = Number(prompt('Enter the value for B: '));
    console.log(`The subtraction result is "${subtraction(a, b)}"`);
    break;

  case '3':
    a = Number(prompt('Enter the value for A: '));
    b = Number(prompt('Enter the value for B: '));
    console.log(`The multiplication result is "${multiplication(a, b)}"`);
    break;

  case '4':
    a = Number(prompt('Enter the value for A (dividend): '));
    b = Number(prompt('Enter the value for B (divisor): '));
    console.log(`The division result is "${division(a, b)}"`);
    break;
}

【问题讨论】：

标签： javascript node.js refactoring

【解决方案1】：

案件之间唯一改变的是

调用的函数
调用的操作的名称
(dividend)(divisor)/

我会为函数和运算符名称使用一个数组——例如，[0] 将引用(a, b) => a + b，因此您只需从用户选择的数字中减去 1 即可访问该函数。要获得a 和b，仅当case 为4 时插入(dividend) (divisor) - 但它可以一次完成。

const fns = [
  [(a, b) => a + b, 'addition'],
  [(a, b) => a - b, 'subtraction'],
  [(a, b) => a * b, 'multiplication'],
  [(a, b) => a / b, 'division']
];
const op = prompt('Operation: ');
const item = fns[op - 1];
if (!item) {
  throw new Error('Invalid');
}
const a = Number(prompt(`Enter the value for A${op === '4' ? ' (dividend)' : ''}: `));
const b = Number(prompt(`Enter the value for b${op === '4' ? ' (divisor)' : ''}: `));
console.log(`The ${item[1]} result is ${item[0](a, b)}`);

【讨论】：

【解决方案2】：

我想你的意思是这样的，对吧？

//Calculator of Basic Operations

function addition(a, b) {
  return (a + b);
}
function subtraction(a, b) {
  return (a - b);
}
function multiplication(a, b) {
  return (a * b);
}
function division(a, b) {
  return (a / b);
}

console.log('Choose the number for the operation you want to use.');
console.log('1 - Addition');
console.log('2 - Subtraction');
console.log('3 - Multiplication');
console.log('4 - Division');

let calcAB = prompt('Operation: ');

switch (calcAB) {
  case '1':
    console.log(`The addition result is "${addition(...enter())}"`);
    break;
  case '2':
    console.log(`The subtraction result is "${subtraction(...enter())}"`);
    break;
  case '3':
    console.log(`The multiplication result is "${multiplication(...enter())}"`);
    break;
  case '4':
    console.log(`The division result is "${...enter())}"`);
    break;
}

function enter() {
  a = Number(prompt('Enter the value for A: '));
  b = Number(prompt('Enter the value for B: '));
  return [a, b];
}

【讨论】：