merge two array into one resultant array

Question

let array1 = [{name:"ABC",add:"XYZ"},{name:"PQR",add:"CCC"}];

let array2 = [1,2]

I want output to be

array1=[{name:"ABC",add:"XYZ",num:1},{name:"PQR",add:"CCC",num:2}];

And I was also wondering if my array2 was also array of object with a weird key name but in resultant array i want a good key name like

let array1 = [{name:"ABC",add:"XYZ"},{name:"PQR",add:"CCC"}];

let array2=[{weirdKey:1},{weirdKey:2}];

but resultant array will be neat like

array1=[{name:"ABC",add:"XYZ",num:1},{name:"PQR",add:"CCC",num:2}];

Will both arrays always be of equal size?

Nicholas K
– Nicholas K

2020-04-07 10:11:53 +00:00
Commented Apr 7, 2020 at 10:11 — Nicholas K
– Nicholas K, Commented Apr 7, 2020 at 10:11
yes both will be same in size

Sanjay Sahani
– Sanjay Sahani

2020-04-07 10:15:35 +00:00
Commented Apr 7, 2020 at 10:15 — Sanjay Sahani
– Sanjay Sahani, Commented Apr 7, 2020 at 10:15

awarrier99 · Accepted Answer · 2020-04-07 10:21:10Z

2

You could do something like the following (assuming the same length for both arrays):

array1 = array1.map((el, i) => {
    el.num = array2[i];
    return el;
});

Edit: For your second case, you can do the following if you're not sure what the weirdKey will be:

array1 = array1.map((el, i) => {
    el.num = Object.values(array2[i])[0];
    return el;
});

edited Apr 7, 2020 at 10:21

answered Apr 7, 2020 at 10:13

awarrier99

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Comments

Nicholas K · Accepted Answer · 2020-04-07 11:13:56Z

1

This following will work for both your scenarios:

let array1 = [{ name: "ABC", add: "XYZ" }, { name: "PQR", add: "CCC" }];
let array2 = [{ weirdKey: 1 }, { weirdKey: 2 }];

array1.forEach((element, i) => {
  array1[i].num = array2[i].weirdKey ? array2[i].weirdKey : array2[i];
});

console.log(array1);

edited Apr 7, 2020 at 11:13

answered Apr 7, 2020 at 10:20

Nicholas K

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5 Comments

Chris Over a year ago

array1[i]["num"] will return the value of num, not the whole object

Nicholas K Over a year ago

Sorry, didn't get what you are trying to convey. But it gives the desired output for either of the conditions.

Chris Over a year ago

you use map to change globally, why?

Nicholas K Over a year ago

OP wanted the change to be applied to array1

Chris Over a year ago

then uses forEach

Abhishek Kulkarni · Accepted Answer · 2020-04-07 10:15:04Z

Try this below :

If array2 is just a list :

let array1 = [{name:"ABC",add:"XYZ"},{name:"PQR",add:"CCC"}];
                let array2 = [1,2];



                array1 = array1.map(function (item_1, index_1) {
                    array2.map(function (item_2, index_2) {
                        if (index_1 == index_2) {
                            item_1['num'] = item_2
                        }
                    });
                    return item_1
                });

                console.log(array1);

If array2 is list of objects , try this below :

array1 = array1.map(function (item_1, index_1) {
                    array2.map(function (item_2, index_2) {
                        if (index_1 == index_2) {
                            item_1['num'] = item_2['weirdKey']
                        }
                    });
                    return item_1
                });

                console.log(array1);

Chris · Accepted Answer · 2020-04-07 10:42:20Z

1

simple pure function:

const combineToArrayFn =
  (array1, array2, key = '') =>
    array1.map((item, i) => ({...item, num: array2[i][key] || array2[i]}));

const newArray = combineToArrayFn(array1, array2);

const newArray1 = combineToArrayFn(array1, array2, 'weirdKey');

edited Apr 7, 2020 at 10:42

answered Apr 7, 2020 at 10:28

Chris

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Comments

Omkar Patil · Accepted Answer · 2020-04-07 11:18:08Z

1

To make it more simpler:

array1.forEach((e,index)=>{
 array1[index]["num"]=array2[index].weirdKey;
});

maybe this can solve your problem.
you can also use simple for loop on array1 instead of forEach() or map() function.

answered Apr 7, 2020 at 11:18

Omkar Patil

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Comments

ironCat · Accepted Answer · 2020-04-07 17:54:42Z

1

try use map() method for arrays

// without weirdKey
let array1 = [{ name: "ABC", add: "XYZ" }, { name: "PQR", add: "CCC" }]
let array2 = [1, 2];

array1.map((item, index) => item.num = (array2[index].weirdKey) ? array2[index].weirdKey : array2[index])
console.log(array1)

// with weirdKey same function
let array3 = [{ name: "ABC", add: "XYZ" }, { name: "PQR", add: "CCC" }]
let array4 = [{ weirdKey: 1 }, { weirdKey: 2 }];

array3.map((item, index) => item.num = (array4[index].weirdKey) ? array4[index].weirdKey : array4[index])
console.log(array3)

answered Apr 7, 2020 at 17:54

ironCat

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2 Comments

Sanjay Sahani Over a year ago

can u tell me when to use map and when to use forEach?

ironCat Over a year ago

forEach use when you don’t need to return any result

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