在javascript中排序前排除特定数组对象

Question

我想知道如何删除(而不是移除)特定的对象，然后在javascript中对嵌套数组对象进行排序，下面是对数组对象进行排序的函数。我需要排除没有数量属性的对象，然后在javascript中对只有数量的对象进行排序，并映射对象(需要使用exluded obj和sorted obj)。

this.providerList = [{id:"transferwise", amount:"1000"}, {id:"wordlremit", amount:"4000", {id:"instarem", amount:"3000"}, {country: "Singapore", scn: "SG"}, {country: "India", scn: "IN"}];

 sortAndFilterProviders() {
    let myList = [];
    myList = [...this.providerList];
    myList.push.apply(myList, this.apiproviderdata.apiproviders);
    // var mergeList = myList.concat(this.query);
    // console.log(mergeList);
    myList.sort(function (a, b) {
      var a1 = a.amount, b1 = b.amount;
      if (a1 == b1) return 0;
      return a1 > b1 ? 1 : -1;
    });
    this.providerList = [...myList];
    return this.providerList;
  }

expected output
  country: Singapore, India
  Sorted Amount : Transferwise , Instarem, Worldremit

Answer 1

您可以使用filter()创建带/不带该属性的数组。然后对所需的数组进行排序。最后，以如下方式对它们进行concat()：

​

let providerList = [{id:"transferwise", amount:"1000"}, {id:"wordlremit", amount:"4000"}, {id:"instarem", amount:"3000"}, {country: "Singapore", scn: "SG"}, {country: "India", scn: "IN"}];

let amount = providerList.filter( item => item.hasOwnProperty('amount')).sort((a,b)=> a.amount - b.amount);
let notAmount = providerList.filter( item => !item.hasOwnProperty('amount'));
var res = notAmount.concat(amount)
console.log(res);

​

Answer 2

您可以首先根据每个元素是否具有amount属性将myList筛选为两个列表：

const includesAmount = myList.filter(item => item.hasOwnProperty('amount'));
const excludesAmount = myList.filter(item => !item.hasOwnProperty('amount'));
includesAmount.sort(...)

const finalArray = [...includesAmount, ...excludesAmount];

这使得两次遍历myList，但是您可以通过迭代遍历myList并将每个元素推送到其各自的数组来在一次遍历中完成。

Answer 3

我不确定为什么上面的答案一定要使用hasOwnProperty()。

简单地检查该属性是否存在会更短且更具可读性：

sortAndFilterProviders() {
  const noAmountList = myList(item => !item['amount']);
  const amountList = myList(item => item['amount']);

  amountList.sort( (a, b) => {
    const a1 = a.amount, 
    b1 = b.amount;
    if (a1 == b1) {
      return 0;
    };
    return a1 > b1 ? 1 : -1;
   });

   console.log(amountList); // check if it is sorted
   return [... noAmountList, amountList];
 }