CODEWITHSUNDEEP
javascript
Kelson Batista
Kelson Batista

Reputation: 492

How to merge two High Order Functions in Javascript

Is there anyway to merge two High Order Functions (HOFs) in Javascript? Basically I have two arrays using map function to get the item, then sum up with another item from another map function.

e.g.

const myArr1 = [
{ attr1: 5, attr2: 9, attr3: 3 },
{ attr1: 4, attr2: 1, attr3: 8 },
{ attr1: 1, attr2: 3, attr3: 1 },
]

const myArr2 = [
{ attr1: 7, attr2: 8, attr3: 5 },
{ attr1: 8, attr2: 2, attr3: 1 },
{ attr1: 3, attr2: 9, attr3: 7 },
]


const map1 = myArr1.map((item) => item);
const map2 = myArr2.map((item) => item);

I need to get something like this (expected):

const total = [{
   attr1: map1.item.attr1 + map2.item.attr1;
   attr2: map1.item.attr2 + map2.item.attr2;
   attr3: map1.item.attr3 + map2.item.attr3;
}, {...}, {...}]

I tried this but did not work as expected:

const total = myArr1.map((item1) => {
   myArr2.map((item2) => {
      return [{
         attr1: item1 + item2,
         attr2: item1 + item2,
         attr3: item1 + item2,
      }, {...}, {...}]
   })
});

Upvotes: 0

Views: 68

Answers (2)

Nicky McCurdy
Nicky McCurdy

Reputation: 19564

You can use a zip function to map over two arrays simultaneously:

import { zip } from "lodash";

const total = zip(myArr1, myArr2).map(([item1, item2]) => ({
    attr1: item1.attr1 + item2.attr1,
    attr2: item1.attr2 + item2.attr2,
    attr3: item1.attr3 + item2.attr3,
}));

Alternatively, you can simplify further with mergeWith:

import { add, mergeWith } from "lodash";

const total = mergeWith([], myArr1, myArr2, (item1, item2) =>
  mergeWith({}, item1, item2, add)
);

Upvotes: 1

Ashirbad Panigrahi
Ashirbad Panigrahi

Reputation: 815

Here it is a simple solution to this

const myArr1 = [
  { attr1: 5, attr2: 9, attr3: 3 },
  { attr1: 4, attr2: 1, attr3: 8 },
  { attr1: 1, attr2: 3, attr3: 1 },
];

const myArr2 = [
  { attr1: 7, attr2: 8, attr3: 5 },
  { attr1: 8, attr2: 2, attr3: 1 },
  { attr1: 3, attr2: 9, attr3: 7 },
];

const myArr3 = myArr1.map((fi, i) => ({
  attr1: fi.attr1 + myArr2[i].attr1,
  attr2: fi.attr2 + myArr2[i].attr2,
  attr3: fi.attr3 + myArr2[i].attr3,
}));

console.log(myArr3); 

/** OUTPUT 
[
  { attr1: 12, attr2: 17, attr3: 8 },
  { attr1: 12, attr2: 3, attr3: 9 },
  { attr1: 4, attr2: 12, attr3: 8 }
]
*/

Upvotes: 2

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