如何删除数组对象中数组内的项目？ javascript

如何解决如何删除数组对象中数组内的项目？ javascript

我想在每个 presentsData 对象中添加一个名为 sumP 的字段，并用 presents 项填充它总和。

第二个目标，如果sumP>钱我想删除里面最贵的项目 它不起作用

const presentsData= [
        {
          name: "Peter",presents: ["coffee","holidays"],money: 7000
        },{
          name: "Mario",presents: ["car","coal"],money: 300
        },{
          name: "Amanda",presents: ["computer",{
          name: "David",presents: ["clothes","car"],money: 2000
        }
    ]
    const prices= [
        {
          present: "coffee",price: 1
        },{
          present: "holidays",price: 1000
        },{
          present: "videogames",price: 40
        },{
          present: "computer",price: 600
        },{
          present: "tattoo",price: 30
        },{
          present: "clothes",price: 80
        },{
          present: "car",price: 6000
        },{
          present: "phone",price: 800
        },{
          present: "motorbike",price: 3500
        },{
          present: "coal",price: 0
        }
      ]
    
    const pricesMap = new Map(prices.map(({ present,price }) => [present,price]))
    
    const res1 =  presentsData.map(s=>{
    return {...s,sumP: s.presents.reduce((acc,p) => acc + pricesMap.get(p),0)
           }
    })
    
     console.log("this is res1=>",res1) //this is presentsData result after adding the field sumP
    
    console.log(pricesMap)
    
    const res2 = res1.map((r)=>{
      if(r.sumP > r.money){
      ( /* would like to delete the item  inside "presents" with the bigger price using pricesMap */)
      }
    })
    
    console.log(res2)

pd：我发现很难找出如何在 presents 中迭代，数组内的对象内的数组。

解决方法

import 'package:async/async.dart' show StreamGroup;

// ... 
Stream<dynamic> stream;
var streamList = <Stream>[];

// ...

void addPeriodicCallToA({Duration period}) {
    streamList.add(Stream<dynamic>.periodic(period,(x) async {
      return await getA();
    }));
  }

// ...

void addPeriodicCallToB({String symbol,Duration period}) {
    streamList.add(Stream<dynamic>.periodic(period,(x) async {
      return await getB(symbol: symbol);
    }));
  }

// ...

addPeriodicCallToA(period: Duration(seconds: 1));
addPeriodicCallToA(period: Duration(symbol: 'yoloandswaglol',seconds: 2));
stream = StreamGroup.merge(streamList);

,

您可以过滤礼物并不断移除最昂贵的礼物，直到有钱购买为止：

const presentsData = [{
    name: "Peter",presents: ["coffee","holidays"],money: 7000
  },{
    name: "Mario",presents: ["car","coal"],money: 300
  },{
    name: "Amanda",presents: ["computer",{
    name: "David",presents: ["clothes","car"],money: 2000
  }
]
const prices = [{
    present: "coffee",price: 1
  },{
    present: "holidays",price: 1000
  },{
    present: "videogames",price: 40
  },{
    present: "computer",price: 600
  },{
    present: "tattoo",price: 30
  },{
    present: "clothes",price: 80
  },{
    present: "car",price: 6000
  },{
    present: "phone",price: 800
  },{
    present: "motorbike",price: 3500
  },{
    present: "coal",price: 0
  }
]

const pricesMap = new Map(prices.map(({
  present,price
}) => [present,price]))

const withSumP = presentsData.map(s => {
  return { ...s,sumP: s.presents.reduce((acc,p) => acc + pricesMap.get(p),0)
  }
})

console.log(withSumP) //this is presentsData result after adding the field sumP

const mostExpensive = (arr) => {
  return arr.reduce((acc,el) => {
    if (pricesMap.get(el) > pricesMap.get(acc)) {
      return el
    }
    return acc;
  })
}

// If you want to remove the most expensive present once for each element
const result = withSumP.map((el) => {
  if (el.sumP > el.money) {
    const presentToDelete = mostExpensive(el.presents);
    return { ...el,presents: el.presents.filter(p => p !== presentToDelete)
    }

  }
  return el;
})

console.log(result);

// If you want to delete presents until you can buy them and also update sumP to be in sync with the presents:

const resultAlt = withSumP.map((el) => {
  let updatedPresents = [...el.presents];
  let updatedSumP = el.sumP;
  while ((updatedSumP > el.money) && (updatedPresents.length > 0)) {
    const presentToDelete = mostExpensive(updatedPresents);
    updatedPresents = updatedPresents.filter(p => p !== presentToDelete);
    updatedSumP -= pricesMap.get(presentToDelete);
  }
  return { ...el,presents: updatedPresents,sumP: updatedSumP
  };
})

console.log(resultAlt)

,

这就是所需要的：

setValue()