Is it possible to sort a ES6 map object for a property of its value object?

Question

I have a Map of object values. I want to sort them for a property of its object values.

Here is the sample Map:

var map = new Map();
map.set("8014",{
            "Access to support": null,
            "Capacity":  1,
            "Comfort Level": null,
            "Control Level": 1,
            "Growth Mindset": 1.5405405405405403,
            "Horizon": null,
            "Motivation": null,
            "Open-Mindedness": null,
            "Proactivity": null,
            "Resiliency": null,
            "Segment": "Level value 1"});
map.set("8015",{
            "Access to support": null,
            "Capacity":  1,
            "Comfort Level": null,
            "Control Level": 1,
            "Growth Mindset": 1.5405405405405403,
            "Horizon": null,
            "Motivation": null,
            "Open-Mindedness": null,
            "Proactivity": null,
            "Resiliency": null,
            "Segment": "Level value 2 or 5"});
map.set("8016",{
            "Access to support": null,
            "Capacity":  1,
            "Comfort Level": null,
            "Control Level": 1,
            "Growth Mindset": 1.5405405405405403,
            "Horizon": null,
            "Motivation": null,
            "Open-Mindedness": null,
            "Proactivity": null,
            "Resiliency": null,
            "Segment": "Level value 3 or 5"});

I want to sort it for Segment property of value object. Any help will be appreciated!

Please create a [mcve] with a valid input, expected output with a clear problem statement. — adiga, Jul 30 '19 at 07:43
is it [`Map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) or just an array? why sorting? — Nina Scholz, Jul 30 '19 at 07:43
Your object is invalid. Also, object keys cannot be sorted. Even if you do sort them, they are not guaranteed to remain in that order. — Kobe, Jul 30 '19 at 07:43
@CertainPerformance, please take a look at the edited version. — DevLoverUmar, Jul 30 '19 at 07:47
If that is a Map, that doesn't look valid. And what's the output - and type of output - meant to be? — Jack Bashford, Jul 30 '19 at 07:50
@JackBashford I'm sorry for inconvenience. Please take a look at updated version. Its a map, I just updated to clearly describe my problem — DevLoverUmar, Jul 30 '19 at 08:00
Maps are ordered (to have predictable iteration), but not sortable. [You need to sort an array](https://stackoverflow.com/q/50069004/1048572) — Bergi, Jul 30 '19 at 08:04
If an answer resolved your issue, please [mark it as accepted](https://meta.stackexchange.com/a/5235/289255) by clicking on the grey checkmark next it. (I'm only mentioning it because you have not accepted any answer till date) — adiga, Jul 30 '19 at 08:30
To accept the answer, you have to click on the grey tick mark button next to the answer: https://i.stack.imgur.com/LkiIZ.png — adiga, Jul 30 '19 at 08:42
You can also check your [previous questions](https://stackoverflow.com/users/7344164/muhammadumarfarooq?tab=questions) and accept the answers if they are resolved too (You get 2 reputation for accepting the answer) — adiga, Jul 30 '19 at 09:07

adiga · Accepted Answer · 2019-07-30T08:27:39.183

You could sort the entries of Map based on Segment by using localeCompare. Then create a new Map from the sorted entries

var map=new Map();map.set("8014",{"Access to support":null,Capacity:1,"Comfort Level":null,"Control Level":1,"Growth Mindset":1.5405405405405403,Horizon:null,Motivation:null,"Open-Mindedness":null,Proactivity:null,Resiliency:null,Segment:"Level value 1"});map.set("8015",{"Access to support":null,Capacity:1,"Comfort Level":null,"Control Level":1,"Growth Mindset":1.5405405405405403,Horizon:null,Motivation:null,"Open-Mindedness":null,Proactivity:null,Resiliency:null,Segment:"Level value 2 or 5"});map.set("8016",{"Access to support":null,Capacity:1,"Comfort Level":null,"Control Level":1,"Growth Mindset":1.5405405405405403,Horizon:null,Motivation:null,"Open-Mindedness":null,Proactivity:null,Resiliency:null,Segment:"Level value 3 or 5"});

const sortedMap =
  new Map(
    Array.from(map)
        .sort((a, b) => a[1].Segment.localeCompare(b[1].Segment))
  );

console.log([...sortedMap.entries()])

no need to get entries, because map returns the entries already. — Nina Scholz, Jul 30 '19 at 08:25

Nina Scholz · Answer 2 · 2019-07-30T08:06:18.540

1

You need to rebuild the Map after sorting the items with a custom callback, because

The Map object holds key-value pairs and remembers the original insertion order of the keys.

const
    customSort = (a, b) => a - b,                           // take your sort function
    sortBy = fn => (a, b) => fn(a[0], b[0]);

var map = new Map([['a', 2], ['c', 1], ['d', 5]]),
    sorted = new Map([...map].sort(sortBy(customSort)));

console.log([...map]);
console.log([...sorted]);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Jul 30 '19 at 08:06

answered Jul 30 '19 at 07:59

Nina Scholz

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`fn(a[1], b[1])` seems simpler than calling a `getValue` function :-) – Bergi Jul 30 '19 at 08:05

Is it possible to sort a ES6 map object for a property of its value object?

2 Answers2