How to Aggregate Multiple Arrays to a Single Array

Question

I have to call an endpoint multiple times and get the responses aggregated to a single array. Below is the response from the endpoint;

{
   items: [
      {key1: value},
      {key2: value}
   ]
}

Below is the code to call the endpoint multiple times;

const chunkedArray = getChunkedArray(largeArray);
const result = await Promise.all(
   chunkedArray.map(async (items) => {
      const response = await ....get(`http:/url/${items}`);
      return response.items;
   });
);

For the result I'm getting below;

[
   [
      {key1: value},
      {key2: value}
   ],
   [
      {key3: value},
      {key4: value}
   ]
]

What I want is an aggregated array like below;

[
   {key1: value},
   {key2: value},
   {key3: value},
   {key4: value}
]

What is the optimum way of doing that?

how you are appending the chunks to the final array?

ozerodb
– ozerodb

2021-05-21 12:34:47 +00:00
Commented May 21, 2021 at 12:34 — ozerodb
– ozerodb, Commented May 21, 2021 at 12:34

Tushar Shahi · Accepted Answer · 2021-05-21 12:43:38Z

1

Try using Array.prototype.flat();

let arr1 = [
   [
      {key1: value},
      {key2: value}
   ],
   [
      {key3: value},
      {key4: value}
   ]
]

let arr2 = arr1.flat(); 
/* [
      {key1: value},
      {key2: value},
      {key3: value},
      {key4: value}
   ] */

If you want to do it without flat you can use reduce too :

let promises = Promise.all(
   chunkedArray.map(async (items) => {
      const response = await ....get(`http:/url/${items}`);
      return response.items;
   });
);

const result =promises.reduce((cum,x) => {
let newArr = await x;
return [...cum,...newArr ];
},[]);

edited May 21, 2021 at 12:43

answered May 21, 2021 at 12:34

Tushar Shahi

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