How do I group objects into an array, if the Date value is the same?

Question

I have an array of objects that looks like the following:

[
    {
        "node_name": "node1",
        "external": "external_node1",
        "status": "online",
        "Date": "2022-05-26 08:20:27.022313"
    },
    {
        "node_name": "node2",
        "external": "external_node2",
        "status": "offline",
        "Date": "2022-05-26 20:20:27.022313"
    },
    {
        "node_name": "node3",
        "external": "external_node3",
        "status": "online",
        "Date": "2022-05-26 08:20:27.022313"
    },
    {
        "node_name": "node4",
        "external": "external_node4",
        "status": "online",
        "Date": "2022-05-26 20:20:27.022313"
    }
]

Using JavaScript, how would I 'group' and insert into its own array, all of the objects that have matching Date values?

For example, node1 & node3 both have "2022-05-26 08:20:27.022313" as its Date value, as well as node2 & node4 having the same Date value.

How would I sort these objects out and insert them into one array if the Date values matched?

This might help you [Filter object array based on category and return list of matches React TS](https://stackoverflow.com/questions/71488008/filter-object-array-based-on-category-and-return-list-of-matches-react-ts/71488557#71488557) — HereBeAndre, May 31 '22 at 14:03

score 0 · Answer 1 · answered May 31 '22 at 14:08

You can achieve it using a combination of sort an reduce:

const data = [
    {
        "node_name": "node1",
        "external": "external_node1",
        "status": "online",
        "Date": "2022-05-26 08:20:27.022313"
    },
    {
        "node_name": "node2",
        "external": "external_node2",
        "status": "offline",
        "Date": "2022-05-26 20:20:27.022313"
    },
    {
        "node_name": "node3",
        "external": "external_node3",
        "status": "online",
        "Date": "2022-05-26 08:20:27.022313"
    },
    {
        "node_name": "node4",
        "external": "external_node4",
        "status": "online",
        "Date": "2022-05-26 20:20:27.022313"
    }
];

const result = data.sort((a,b) => Date.parse(a.Date) - Date.parse(b.Date)).  
reduce((acc, data) => {
    const date = data.Date;
    acc[date] = acc[date] || [];
    acc[date] = [...acc[date], data];
    return acc;
}, {})

console.log(result);

score 0 · Accepted Answer · answered May 31 '22 at 14:11

I would suggest using Array.reduce() to convert the input to the desired form.

You can wrap this in a groupBy() function. This will return an object with an array of objects for each value encountered.

const input = [ { "node_name": "node1", "external": "external_node1", "status": "online", "Date": "2022-05-26 08:20:27.022313" }, { "node_name": "node2", "external": "external_node2", "status": "offline", "Date": "2022-05-26 20:20:27.022313" }, { "node_name": "node3", "external": "external_node3", "status": "online", "Date": "2022-05-26 08:20:27.022313" }, { "node_name": "node4", "external": "external_node4", "status": "online", "Date": "2022-05-26 20:20:27.022313" } ]
 
function groupBy(arr, key) {
    return arr.reduce((acc, el) => { 
        acc[el[key]] = [...(acc[el[key]] || []), el];
        return acc;
    }, {})
}

const result = groupBy(input, 'Date');
console.log('Result:', result)

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

score 0 · Answer 3 · answered May 31 '22 at 14:12

Use javascript's .filter() method.

const newArray = oldArray.filter(data => {
    return data.Date == "2022-05-26 08:20:27.022313"
})

This will return all the objects with date value as above (2022-05-26 08:20:27.022313) i.e. node1 and node3 into a different array.

How do I group objects into an array, if the Date value is the same?

3 Answers3