How to Sort Map Objects using object values

Question

How do I sort this kind of map using the field lastSeen

var clients = new Map();
clients.set("BOJ_iPWtI7jVvG_pAAAH", {name: "John", lastSeen: 1608192766697});
clients.set("cShpndAsircj4_P4AAAN", {name: "Doe", lastSeen: 1608192862339});

How do I sort this clients map using lastSeen.

I have tried like this:

var sortedClients = new Map([...clients.entries()].sort((a,b)=>b.lastSeen - a.lastSeen));

but it is not working so I know I am not doing the right thing.

log a and b values inside the compareFunction. entries returns an array of key-value pairs. So, a will be something like: ["BOJ_iPWtI7jVvG_pAAAH", {name: "John", lastSeen: 1608192766697}] — adiga
– adiga, Commented Dec 17, 2020 at 8:39

PIG208 · Accepted Answer · 2020-12-17 08:39:24Z

3

Use b[1].lastSeen instead of b.lastSeen and the same for a as well, because the attribute lastSeen is actually in index 1 for each entry in clients.

var sortedClients = new Map([...clients.entries()].sort((a,b)=>b[1].lastSeen - a[1].lastSeen));

answered Dec 17, 2020 at 8:39

PIG208

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Md Sabbir Alam · Accepted Answer · 2020-12-17 08:40:37Z

2

You can do the following,

var clients = new Map();
clients.set("BOJ_iPWtI7jVvG_pAAAH", {name: "John", lastSeen: 1608192766697});
clients.set("cShpndAsircj4_P4AAAN", {name: "Doe", lastSeen: 1608192862339});
var mapAsc = new Map([...clients.entries()].sort((a, b) => {
  if(a[1].lastSeen > b[1].lastSeen) {
    return -1;
  } else if(a[1].lastSeen < b[1].lastSeen) {
    return 1;
  } else {
    return 0;
  }
}));
console.log(mapAsc);

answered Dec 17, 2020 at 8:40

Md Sabbir Alam

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1 Comment

Richard Ochom Over a year ago

Thanks to your answer, I understand what goes on inside the sort(); but I'll accept @PIG208 answer cause it's precise.

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