如何获取集合中每个发件人的最新消息？

Question

我有一个这样的对象数组：const messages = [   {message: "ghhhhhhhh", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "14", time: "12:56"},  {message: "ggggggghjjgcgh", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "ZCiuWczin3VuibH59MISuEqR3pc2", time: "12:45"},  {message: "good afternoon", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "ZCiuWczin3VuibH59MISuEqR3pc2", time: "12:41"},  {message: "hfdsghfdfhjo", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "ZCiuWczin3VuibH59MISuEqR3pc2", time: "12:38"},  {message: "hhhhhhhhhhhhh ", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "14", time: "11:50"}];我想获取每个发件人的最新消息，如下所示：const messages = [  {message: "ghhhhhhhh", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "14", time: "12:56"},  {message: "ggggggghjjgcgh", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "ZCiuWczin3VuibH59MISuEqR3pc2", time: "12:45"}];怎么做？

Answer 1

您可以为此目的使用 array.reduce，例如：

const messages = [ {message: "ghhhhhhhh", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "14", time: "12:56"}

, {message: "ggggggghjjgcgh", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "ZCiuWczin3VuibH59MISuEqR3pc2", time: "12:45"}

, {message: "good afternoon", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "ZCiuWczin3VuibH59MISuEqR3pc2", time: "12:41"}

, {message: "hfdsghfdfhjo", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "ZCiuWczin3VuibH59MISuEqR3pc2", time: "12:38"}

, {message: "hhhhhhhhhhhhh ", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "14", time: "11:50"}];

function parseTime(timeStr) {

    const fields = timeStr.split(":").map(parseInt);

    return fields[0] * 60 + fields[1];

}

let result = messages.reduce( (map, item) => { 

   if (!map[item.sender] || parseTime(map[item.sender].time) < parseTime(item.time)) {

       map[item.sender] = item;

   } 

   return map;

}, {});

console.log("Latest messages:", Object.values(result));

Answer 2

你可以这样做： -

const messages = [ {message: "ghhhhhhhh", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "14", time: "12:56"}

, {message: "ggggggghjjgcgh", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "ZCiuWczin3VuibH59MISuEqR3pc2", time: "12:45"}

, {message: "good afternoon", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "ZCiuWczin3VuibH59MISuEqR3pc2", time: "12:41"}

, {message: "hfdsghfdfhjo", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "ZCiuWczin3VuibH59MISuEqR3pc2", time: "12:38"}

, {message: "hhhhhhhhhhhhh ", receiver: "OX0pReHXfXUTq1XnOnTSX7moiGp2", sender: "14", time: "11:50"}]

const getUniqueMessages = (messages) => {

    const msgMap = {};

    const uniqueMsg = [];

    messages.forEach(item => {

        if(!msgMap[item.sender]) {

            msgMap[item.sender] = true;

            uniqueMsg.push(item)

        }

    });

   return uniqueMsg;   

}

// console.log(getUniqueMessages(messages));

Answer 3

const result = [];

const map = new Map();

for (const item of messages) {

    if(!map.has(item.sender)){

        map.set(item.sender, true);

        result.push({

            message: item.message,

    reciever: item.reciever

            sender: item.sender,

            time: item.time

        });

    }

}

console.log(result)