如何从数组中的 object 中删除相同的日期字符串？

Question

Hello I have a array like this.

const array = [
{date: "2022-02-22 18:00:00"}
{date: "2022-02-22 17:00:00"}
{date: "2022-02-22 18:00:00"}
{date: "2022-02-23 01:00:00"}
{date: "2022-02-23 10:00:00"}
{date: "2022-02-24 18:00:00"}
]

Here I have to keep only one object for each day. Here It should be like that-

[
{date: "2022-02-22 18:00:00"}
{date: "2022-02-23 01:00:00"}
{date: "2022-02-24 18:00:00"}
]

Here you can see 22, 23, 24 date object. Not same date twice. Can anyone help me. I can also use moments js. You I need to use momentjs then please tell me.

Answer 1

There are many ways to accomplish that: This is one

 const data = [ {date: "2022-02-22 18:00:00"}, {date: "2022-02-22 17:00:00"}, {date: "2022-02-22 18:00:00"}, {date: "2022-02-23 01:00:00"}, {date: "2022-02-23 10:00:00"}, {date: "2022-02-24 18:00:00"} ]; // simplified explanation: let reminder = []; let result = data.filter( item => { // 1st iteration: | 2nd iteration: | 3rd iteration: | 4th iteration: | 5th iteration: let date = item.date.split(' ')[0]; // 2022-02-22 | 2022-02-22 | 2022-02-22 | 2022-02-23 | 2022-02-24 if(reminder.includes(date)) { // does not include | reminder has this | reminder has this | does not include | does not include return false; // will not get here | go to next item | go to next item | will not get here | will not get here } reminder.push(date); // push to reminder | (will never reach | (will never reach | push to reminder | push to reminder return true; // add to result | those lines) | those lines) | add to result | add to result }); console.log('result', result)

Read more about the used functions: Array.filter() , String.split() , Array.includes() and Array.push()

Update, as discussed in the comments

If you are dealing with a big amount of data you may better use new Set() with Set.has() and Set.add() see the next example using new Set()

 const data = [ {date: "2022-02-22 18:00:00"}, {date: "2022-02-22 17:00:00"}, {date: "2022-02-22 18:00:00"}, {date: "2022-02-23 01:00:00"}, {date: "2022-02-23 10:00:00"}, {date: "2022-02-24 18:00:00"} ]; // simplified explanation: let reminder = new Set(); let result = data.filter( item => { // 1st iteration: | 2nd iteration: | 3rd iteration: | 4th iteration: | 5th iteration: let date = item.date.split(' ')[0]; // 2022-02-22 | 2022-02-22 | 2022-02-22 | 2022-02-23 | 2022-02-24 if(reminder.has(date)) { // does not have | reminder has this | reminder has this | does not have | does not have return false; // will not get here | go to 3rd | go to 4th | will not get here | will not get here } reminder.add(date); // push to reminder | (will never reach | (will never reach | push to reminder | push to reminder return true; // add to result | those lines) | those lines) | add to result | add to result // go to 2nd | | | go to 5th | finished }); console.log('result', result);

Answer 2

The following should be what you want. Please let me know if this works for you.

const array = [
    {date: "2022-02-22 18:00:00"},
    {date: "2022-02-22 17:00:00"},
    {date: "2022-02-22 18:00:00"},
    {date: "2022-02-23 01:00:00"},
    {date: "2022-02-23 10:00:00"},
    {date: "2022-02-24 18:00:00"}
]

// Slice first 10 characters of array and check for duplicates. Keep first element found.
const unique = array.reduce((acc, curr) => {
    if (acc.length === 0) {
        acc.push(curr)
    } else {
        const found = acc.find(e => e.date.slice(0, 10) === curr.date.slice(0, 10))
        if (!found) {
            acc.push(curr)
        }
    }
    return acc
}, [])

console.log(unique)