Question

我想从一个对象数组中创建一个对象数组，这是数据：

// Input:
const shippingMethodOptions = [{
  id: 1,
  carrier_token: 'fedex',
  carrier_name: 'Fedex',
  weight: 1,
  price: 3
}, {
  id: 2,
  carrier_token: 'fedex',
  carrier_name: 'Fedex',
  weight: 2,
  price: 6
}, {
  id: 3,
  carrier_token: 'fedex',
  carrier_name: 'Fedex',
  weight: 6,
  price: 9
}, {
  id: 4,
  carrier_token: 'usps',
  carrier_name: 'Usps',
  weight: 6,
  price: 9
}, {
  id: 5,
  carrier_token: 'delaware',
  carrier_name: 'Delaware',
  weight: 5,
  price: 10
}]

正如您所看到的数据有carrier_token和carrier_name，我想要的是创建一个具有唯一carriers的输出数组，如下所示：

// Output:
const carriers = [{
  carrier_token: 'fedex',
  carrier_name: 'Fedex'
}, {
  carrier_token: 'usps',
  carrier_name: 'USPS'
}, {
  carrier_token: 'delaware',
  carrier_name: 'Delaware'
}]

我试过用for循环构建它，但是我想知道这是否可以以更干净的方式进行（减少？）

这是我目前的解决方案（但同样，我很想知道是否可以通过Reduce等使其更清洁。）

const getCarriers = options => {
  const carriers = []

  options.forEach(({ carrier_token, carrier_name }) => {
    const foundIndex = _.findIndex(carriers, carrier => carrier.carrier_token === carrier_token)

    if (foundIndex !== -1) {
      return
    }

    carriers.push({
      carrier_token,
      carrier_name
    })
  })

  return carriers
}

const carriers = getCarriers(shippingMethodOptions)

Answer 1

似乎是一个非常简单的 reduce 工作。

您需要的是一种跟踪现有运营商的方法。我建议使用Set并存储由令牌和名称制作的密钥，例如在"<token>:<name>"之类的字符串中。

＆＃13;

const shippingMethodOptions = [{"id":1,"carrier_token":"fedex","carrier_name":"Fedex","weight":1,"price":3},{"id":2,"carrier_token":"fedex","carrier_name":"Fedex","weight":2,"price":6},{"id":3,"carrier_token":"fedex","carrier_name":"Fedex","weight":6,"price":9},{"id":4,"carrier_token":"usps","carrier_name":"Usps","weight":6,"price":9},{"id":5,"carrier_token":"delaware","carrier_name":"Delaware","weight":5,"price":10}]

const carriers = shippingMethodOptions.reduce(function(arr, smo) {
  let key = `${smo.carrier_token}:${smo.carrier_name}`
  return this.has(key) ? arr : this.add(key) && arr.concat({
    carrier_token: smo.carrier_token,
    carrier_name: smo.carrier_name
  });
}.bind(new Set()), [])

console.info(carriers)

＆＃13;

我将Set绑定到reduce回调，因此可以通过this关键字使用它，但您可以在回调范围和商店之外轻松创建它它在变量中，例如

const keys = new Set()

Answer 2

我考虑将.reduce()与Map()一起使用，其中地图条目包含基于${carrier_token}:${carrier_name}的键和所需对象格式的值。然后在地图的Array.from()上使用.values()。

const shippingMethodOptions = [{"id":1,"carrier_token":"fedex","carrier_name":"Fedex","weight":1,"price":3},{"id":2,"carrier_token":"fedex","carrier_name":"Fedex","weight":2,"price":6},{"id":3,"carrier_token":"fedex","carrier_name":"Fedex","weight":6,"price":9},{"id":4,"carrier_token":"usps","carrier_name":"Usps","weight":6,"price":9},{"id":5,"carrier_token":"delaware","carrier_name":"Delaware","weight":5,"price":10}]

const carriers = Array.from(
  shippingMethodOptions.reduce((map, {carrier_token, carrier_name}) => {
    const key = `${carrier_token}:${carrier_name}`
    if (!map.has(key)) map.set(key, { carrier_token, carrier_name })
    return map
  }, new Map()).values()
)

console.log(carriers)

或者，只要carrier_token足以实现唯一性，您就可以简化它：

const shippingMethodOptions = [{"id":1,"carrier_token":"fedex","carrier_name":"Fedex","weight":1,"price":3},{"id":2,"carrier_token":"fedex","carrier_name":"Fedex","weight":2,"price":6},{"id":3,"carrier_token":"fedex","carrier_name":"Fedex","weight":6,"price":9},{"id":4,"carrier_token":"usps","carrier_name":"Usps","weight":6,"price":9},{"id":5,"carrier_token":"delaware","carrier_name":"Delaware","weight":5,"price":10}]

const carriers = Array.from(
  shippingMethodOptions.reduce((map, {carrier_token, carrier_name}) => {
    if (!map.has(carrier_token)) map.set(carrier_token, { carrier_token, carrier_name })
    return map
  }, new Map()).values()
)

console.log(carriers)

Javascript：使用reduce / map等创建具有特定值的对象数组

2 个答案: