Group array with a given id in javascript

Question

I pass an array and an id to a function, this function will group that array by id.

id = "f58d5d3a6c4"; // id is read-only
array = [
    {createOn: "2021-02-06T18:03:13.915", message: "Hello Subscriber"},
    {createOn: "2021-02-06T18:03:42.462", message: "New Messages"},
    {createOn: "2021-01-29T14:21:01.761", message: "Hello"},
    {createOn: "2021-02-06T18:02:56.145", message: "Hello Subscriber"}
]

I want to group the above array like so:

"f58d5d3a6c4": [
    {createOn: "2021-02-06T18:03:13.915", message: "Hello Subscriber"},
    {createOn: "2021-02-06T18:03:42.462", message: "New Messages"},
    {createOn: "2021-01-29T14:21:01.761", message: "Hello"},
    {createOn: "2021-02-06T18:02:56.145", message: "Hello Subscriber"}
]

This is my code, but I just get an empty array after console.log it out:

const group = array.reduce((r, a) => {
    var key = id;
    key = [...(r || []), a];
    return r;
}, []);

Can you help me how to fix that? Thank you.

Snow · Accepted Answer · 2021-03-03 04:51:35Z

1

Complicated, why not just

id = "f58d5d3a6c4"; // id is read-only
array = [
    {createOn: "2021-02-06T18:03:13.915", message: "Hello Subscriber"},
    {createOn: "2021-02-06T18:03:42.462", message: "New Messages"},
    {createOn: "2021-01-29T14:21:01.761", message: "Hello"},
    {createOn: "2021-02-06T18:02:56.145", message: "Hello Subscriber"}
]


const newObj = {
  [id]: array
};
console.log(newObj);

answered Mar 3, 2021 at 4:51

Snow

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3 Comments

Linh Nguyễn Over a year ago

Oh. Perhaps I thought it was too complicated. :)) Thank you

Linh Nguyễn Over a year ago

But what if I want to return an array? like ["f58d5d3a6c4": [....]]

Snow Over a year ago

That syntax is not valid.

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