使用Angular 6中的时间戳，仅过滤对象中具有相同ID的最新数据 [英] Filter only the latest data for the same ID in an object, using timestamp in Angular 6

问题描述

我有一个存储在'component'变量中的对象数组

I have an array of objects stored in 'component' variable

component=[{id:1,date:'20-10-2020'},{id:1,date:'13-01-2020'},{id:2,date:'30-03-2020'}]

在这里，我有2个对象，它们的"id"相同(id:1)，但日期不同.如果其中有多个具有相同ID的对象，我只需要取出具有最新日期的ID.可以使用过滤器吗?

Here I'm having 2 objects with 'id' as same(id:1) but with different dates. If there are multiple objects with the same id in it, I need to take out only the id with the latest date. Is it possible with filters?

过滤后，我需要输出类似

After filtering, I need the output like

component=[{id:1,date:'20-10-2020'},{id:2,date:'30-03-2020'}]

此处'{id:1，date:'13 -01-2020'}'已从阵列中删除.

Here '{id:1,date:'13-01-2020'}' is removed from the array.

预先感谢

推荐答案

您可以使用以下使用Map的代码来做到这一点:

You may do so using the following code which makes use of a Map:

let map = new Map();

component.forEach(e => {
  if (map.get(e.id) !== undefined) {     
    // current date
    const [newDay, newMonth, newYear] = e.date.split("-")
    let newDate = new Date(newYear, newMonth - 1, newDay);
    
    // previous date
    const [oldDay, oldMonth, oldYear] = map.get(e.id).split("-")
    let oldDate = new Date(oldYear, oldMonth - 1, oldDay);
    
    // compare the date and pick the latest
    map.set(e.id, newDate > oldDate ? e.date : map.get(e.id));
  } else {
    map.set(e.id, e.date);
  }
});

// clear the original contents
component = [];

// now populate it from the map
for (let e of map.entries()) {
   component.push({id: e[0], date: e[1]});
}
console.log(component);

这篇关于使用Angular 6中的时间戳，仅过滤对象中具有相同ID的最新数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！