按日期对嵌套的对象数组进行排序

Question

I have an array of users objects with several key value pairs, and I wanted to sort users base on createdAt that in chatInfo array

[
    {
        _id: "1",
        age: "30",
        chatInfo: [
            {
                chatId: "22",
                createdAt: "2020-07-07T00:39:30.571Z",
                seen: false,
                senderEmail: "debot73186@klefv.com",
            },
        ],
    },
    {
        _id: "2",
        age: "21",
        chatInfo: [
            {
                chatId: "22",
                createdAt: "2020-07-07T20:08:33.171Z",
                seen: false,
                senderEmail: "debot73186@klefv.com",
            },
        ],
    },
];

Update

I tried this with underscore

const sorting = (arr)=>  {
    for (let i = 0; i < arr.length; i++) {
        const user = arr[i];
        user.chatInfo.sort((a, b) => {
            return new Date(a.createdAt).getTime() - new Date(b.createdAt).getTime();
        });
    }
    return _.sortBy(arr, "chatInfo");
}

Answer 1

You can sort elements of JavaScript arrays using the built-in sort method. In order for it to work as intended, we need to compare the the ISO timestamps by its numerical value.

You can easily construct Date objects with an ISO timestamp string. Using the getTime method will return its numerical representation in milliseconds. The milliseconds can then be compared in a basic sort function.

yourArray.sort((a, b) => {
  return new Date(a.chatInfo[0].createdAt).getTime() < new Date(b.chatInfo[0].createdAt).getTime() ? -1 : 1
});

Depending on whether you need it sorted in ascending or descending order, simply flip the comparison operator to and from < and > .