根据时间戳删除数组中的"like items"对象

Question

我有一个数组(可能不止这个(，它有一个uid和一个timestamp。

我的目标是循环浏览一个对象，如果它们的uid相等，则只保留具有较大时间戳的对象。

[
{
"uid":"u55555",
"timestamp":1536273731,
"id":"8a655addf1293b6d780ff6469c0848dd",
"name":"John Doe",
},
{
"uid":"u55555",
"timestamp":1536273831,
"id":"8v8799817981mcmccm89c81282128cm2",
"name":"John Doe",
},
{
"uid":"u1111",
"timestamp":1536253940,
"id":"c8898202n2nu929n2828998228989h2h2",
"name":"Test Testerson",
},
{
"uid":"u55555",
"timestamp":1536274940,
"id":"fb990b1734e4aaea2e39315952e13123",
"name":"John Doe",
},
{
"uid":"u11111",
"timestamp":1538275741,
"id":"99s9hshs88s8g89898899898897a79s",
"name":"Test Testerson",
},
]

有谁知道我会怎么做？

我一直在玩以下方法，但无法使其恰到好处。

var result = signatures.filter(function (a) {
//logic here
}, Object.create(null));

Answer 1

您可以按时间戳对原始数组进行排序，然后使用sort和reduce将其减少为一组唯一的uid。

var data = [{"uid": "u55555","timestamp": 1536273731,"id": "8a655addf1293b6d780ff6469c0848dd","name": "John Doe",}, { "uid": "u55555", "timestamp": 1536273831, "id": "8v8799817981mcmccm89c81282128cm2", "name": "John Doe", }, { "uid": "u1111", "timestamp": 1536253940, "id": "c8898202n2nu929n2828998228989h2h2", "name": "Test Testerson", }, { "uid": "u55555", "timestamp": 1536274940, "id": "fb990b1734e4aaea2e39315952e13123", "name": "John Doe", }, { "uid": "u11111", "timestamp": 1538275741, "id": "99s9hshs88s8g89898899898897a79s", "name": "Test Testerson", }];
var result = data
.sort((a,b) => b.timestamp - a.timestamp) //Sort by timestamp descending
.reduce((a,i) => a.some(n=>n.uid === i.uid) ? a : [...a, i], []); //If item is already accounted for, ignore it
console.log(result);

Answer 2

您可以创建一个以guid为键的对象，并在数组中循环将该项添加到对象(如果它尚不存在或时间更短(。然后只需从该对象中获取值：

let arr = [{"uid":"u55555","timestamp":1536273731,"id":"8a655addf1293b6d780ff6469c0848dd","name":"John Doe",},{"uid":"u55555","timestamp":1536273831,"id":"8v8799817981mcmccm89c81282128cm2","name":"John Doe",},{"uid":"u1111","timestamp":1536253940,"id":"c8898202n2nu929n2828998228989h2h2","name":"Test Testerson",},{"uid":"u55555","timestamp":1536274940,"id":"fb990b1734e4aaea2e39315952e13123","name":"John Doe",},{"uid":"u11111","timestamp":1538275741,"id":"99s9hshs88s8g89898899898897a79s","name":"Test Testerson",},]
let newArr = Object.values(
arr.reduce((obj, item) => {
if (!obj[item.uid] || obj[item.uid].timestamp < item.timestamp)
obj[item.uid] = item
return obj
}, {}))
console.log(newArr)

Answer 3

您可以找到该对象并检查时间戳或将实际对象添加到结果集中。

var array = [{ uid: "u55555", timestamp: 1536273731, id: "8a655addf1293b6d780ff6469c0848dd", name: "John Doe" }, { uid: "u55555", timestamp: 1536273831, id: "8v8799817981mcmccm89c81282128cm2", name: "John Doe" }, { uid: "u1111", timestamp: 1536253940, id: "c8898202n2nu929n2828998228989h2h2", name: "Test Testerson" }, { uid: "u55555", timestamp: 1536274940, id: "fb990b1734e4aaea2e39315952e13123", name: "John Doe" }, { uid: "u11111", timestamp: 1538275741, id: "99s9hshs88s8g89898899898897a79s", name: "Test Testerson" }],
result = array.reduce((r, o) => {
var index = r.findIndex(({ uid }) => uid === o.uid);
if (index === -1) {
return r.concat(o);
}
if (o.timestamp > r[index].timestamp) {
r[index] = o;
}
return r;
}, []);
console.log(result);

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Answer 4

这将创建一个新对象，该对象使用基于 UID 的键;然后仅用最后一个条目填充它。也许不是最小的代码，但它是一种方法。

let sorted = {};
let original = [{
"uid": "u55555",
"timestamp": 1536273731,
"id": "8a655addf1293b6d780ff6469c0848dd",
"name": "John Doe",
},
{
"uid": "u55555",
"timestamp": 1536273831,
"id": "8v8799817981mcmccm89c81282128cm2",
"name": "John Doe",
},
{
"uid": "u11111",
"timestamp": 1536253940,
"id": "c8898202n2nu929n2828998228989h2h2",
"name": "Test Testerson",
},
{
"uid": "u55555",
"timestamp": 1536274940,
"id": "fb990b1734e4aaea2e39315952e13123",
"name": "John Doe",
},
{
"uid": "u11111",
"timestamp": 1538275741,
"id": "99s9hshs88s8g89898899898897a79s",
"name": "Test Testerson",
},
];
original.forEach((item) => {
if (sorted[item.uid] == undefined || sorted[item.uid].timestamp < item.timestamp) {
// if key doesn't exist, create it
// if key exists but timestamp is newer, replace it
sorted[item.uid] = {
uid: item.uid,
timestamp: item.timestamp,
id: item.id,
name: item.name
}
}
});
console.log(sorted);