Question

我有一系列对象，如下所示，

[    
    {time: 1526577280000, operationType: "CREATE", path: "users/111"},
    {time: 1526563418000, operationType: "DELETE", path: "users/111"},
    {time: 1526557418000, operationType: "CREATE", path: "users/111"},
    {time: 1526557280000, operationType: "CREATE", path: "users/123"},
    {time: 1526557223000, operationType: "CREATE", path: "users/345"},
    {time: 1526553596000, operationType: "DELETE", path: "users/222"},
    {time: 1526553444000, operationType: "CREATE", path: "users/222"}
]

如何根据最新的timestamp即time，仅从重复路径返回最新的单个路径。有些对象具有基于operationType的相同路径，我只想从具有多个相同路径的对象返回最新路径。

Answer 1

首先，您需要定义条目重复项的时间。我理解它的方式，他们的operationType 和 path需要相等，但time可能会有所不同。这给了我们：

const equal = (x, y) => (
  x.operationType === y.operationType &&
  x.path === y.path
);

现在，在循环所有条目时，我们不一定要检查所有其他条目是否相等。这就是为什么我们会采用不同的方式来跟踪我们的进度。我们将定义一个hash函数，将对象序列化为可比较的字符串：

const hash = e => [e.operationType, e.path].join("__");

现在，我们可以循环我们的数据一次并检查该条目是第一个哈希，还是比前一个更旧：

＆＃13;

const data = [    
    {time: 1526577280000, operationType: "CREATE", path: "users/111"},
    {time: 1526563418000, operationType: "DELETE", path: "users/111"},
    {time: 1526557418000, operationType: "CREATE", path: "users/111"},
    {time: 1526557280000, operationType: "CREATE", path: "users/123"},
    {time: 1526557223000, operationType: "CREATE", path: "users/345"},
    {time: 1526553596000, operationType: "DELETE", path: "users/222"},
    {time: 1526553444000, operationType: "CREATE", path: "users/222"}
];

const hash = e => [e.operationType, e.path].join("__");
const latestUniques = Object.values(data.reduce(
  (map, e) => {
    const key = hash(e);
    
    if (!map[key] || map[key].time > e.time) {
      map[key] = e;
    }
    
    return map;
    
  },
  {}
));

console.log(latestUniques);

＆＃13;

Answer 2

尝试这样的事情

array.sort( function(one, two){ return one.time < two.time } )[0].path;

从重复对象数组中返回最新值

2 个答案: