Question

我有一个数组：

var arr = [
  {price: 5, amount: 100},
  {price: 3, amount: 50},
  {price: 10, amount: 20},
  {price: 3, amount: 75},
  {price: 7, amount: 15},
  {price: 3, amount: 65},
  {price: 2, amount: 34}
]

我想删除具有相同价格的重复项，并且只保留最后一个副本，然后根据价格从最高到最低对数组进行排序。这是我想要的结果：

var result = [
  {price: 10, amount: 20},
  {price : 7, amount: 15},
  {price: 5, amount: 100},
  {price: 3, amount: 65},
  {price: 2, amount: 34}
]

Answer 1

使用reduce将对象首先转换为删除副本，最后一个副本应覆盖前一个

var obj = arr.reduce( ( acc, c ) =>  Object.assign(acc, {[c.price]:c.amount}) , {});

将其转换回数组并对其进行排序

var output = Object.keys( obj )
              .map( s => ({ price : s, amount : obj[ s ] }) )
              .sort( ( a, b )  => b.price - a.price );

<强>演示

var arr = [
  {price: 5, amount: 100},
  {price: 3, amount: 50},
  {price: 10, amount: 20},
  {price: 3, amount: 75},
  {price: 7, amount: 15},
  {price: 3, amount: 65},
  {price: 2, amount: 34}
];
var obj = arr.reduce( ( acc, c ) =>  Object.assign(acc, {[c.price]:c.amount}) , {});
var output = Object.keys( obj )
              .map( s => ({ price : s, amount : obj[ s ] }) )
              .sort( ( a, b )  => b.price - a.price );
console.log( output );

Answer 2

您可以使用Array.reduce汇总数组中的结果：

var arr = [
  {price: 5, amount: 100},
  {price: 3, amount: 50},
  {price: 10, amount: 20},
  {price: 3, amount: 75},
  {price: 7, amount: 15},
  {price: 3, amount: 65},
  {price: 2, amount: 34}
]

var results = arr.reduce<{ [price: string] : typeof arr[0] }>((p, e)=> {
    p[e.price] = e
    return p;
}, {});

var resultsAsArray = Object.keys(results)
     .map(k=>results[k])
     .sort((a, b) => b.price - a.price);

如果定义了数组项，则可以将typeof arr[0]替换为数组项的类型。

解决方案的想法是在价格为关键的对象中累积结果，如果多次遇到相同的键，则旧值被覆盖到最后您只有最后一个值给定价格。

Answer 3

我使用 reduceRight 和 splice 删除重复项。它不会创建任何无用的中间对象，只是一路上找到的独特价格列表：

＆＃13;

var arr = [
  {price: 5, amount: 100},
  {price: 3, amount: 50},
  {price: 10, amount: 20},
  {price: 3, amount: 75},
  {price: 7, amount: 15},
  {price: 3, amount: 65},
  {price: 2, amount: 34}
]

arr.reduceRight((acc, obj, i) => {
  acc[obj.price]? arr.splice(i, 1) : acc[obj.price] = true;
  return acc;
}, Object.create(null));

arr.sort((a, b) => b.price - a.price);

console.log(arr)

＆＃13;

Javascript es6 - 如何删除对象数组中的重复项，除了最后一个副本？

3 个答案: