Let you better write the skills of conditional statements in JavaScript (ES6)

1. Use Array.includes to handle multiple conditions 

general:

// condition
function test(fruit) {
  if (fruit == 'apple' || fruit == 'strawberry') {
    console.log('red');
  }
}

optimization: 

function test(fruit) {
  // 条件提取到数组中
  const redFruits = ['apple', 'strawberry', 'cherry', 'cranberries'];

  if (redFruits.includes(fruit)) {
    console.log('red');
  }
}

2. Choose Map / Object literal instead of Switch statement

general:

function test(color) {
  // 使用 switch case 语句，根据颜色找出对应的水果
  switch (color) {
    case 'red':
      return ['apple', 'strawberry'];
    case 'yellow':
      return ['banana', 'pineapple'];
    case 'purple':
      return ['grape', 'plum'];
    default:
      return [];
  }
}

//测试结果
test(null); // []
test('yellow'); // ['banana', 'pineapple']

optimization:

// 使用对象字面量，根据颜色找出对应的水果
  const fruitColor = {
    red: ['apple', 'strawberry'],
    yellow: ['banana', 'pineapple'],
    purple: ['grape', 'plum']
  };

function test(color) {
  return fruitColor[color] || [];
}

Alternatively, you can use Map to achieve the same result:

// 使用 Map ，根据颜色找出对应的水果
  const fruitColor = new Map()
    .set('red', ['apple', 'strawberry'])
    .set('yellow', ['banana', 'pineapple'])
    .set('purple', ['grape', 'plum']);

function test(color) {
  return fruitColor.get(color) || [];
}

Reference: https://mp.weixin.qq.com/s/T6QWwA1v7GfnBTrgynsfzA