1.利用Array.includes

不好的写法：

const func = name => {
  if (name === 'Jerry' || name === 'Tom' || name === 'Speike') {
    // do somathing
  }
}

利用Array.includes重构：

const names = [
  'Jerry',
  'Tom',
  'Speike'
];
const func = name => {
  if (names.includes(name)) {
    // do somathing
  }
}

2.使用对象代替多个if或switch

不好的写法：

const getRace = name => {
  switch(name) {
    case 'Jerry':
      return 'mouse';
      breake;
    case 'Tom':
      return 'cat';
      breake;
    case 'Speike':
      return 'dog';
      breake;
    default:
      return 'animal';
  }
}

使用对象重构：

const raceObj = {
  Jerry: 'mouse',
  Tom: 'cat',
  Speike: 'dog'
}
const getRace = name => {
  return raceObj[name] || 'animal';
}

3.提前return，而不是嵌套判断

不好的写法：

const getAnimalInfo = animal => {
  let animalInfo;
  if (animal) {
    if (animal.name) {
      if (animal.age) {
        animalInfo = `Name: ${animal.name},age: ${animal.age}`;
      } else {
        animalInfo = 'No age';
      }
    } else {
      animalInfo = 'No name';
    }
  } else {
    animalInfo = 'No animal';
  }

  return animalInfo;
}

重构：

const getAnimalInfo = animal => {
  if (!animal) return 'No animal';
  if (!animal.name) return 'No name';
  if (!animal.age) return 'No age';
  return `Name: ${animal.name},age: ${animal.age}`;
}