How split inner array in array?

Question

I have an array of object. One object has an array inside.

var array = [{ a:'ai', b:'bi', c:['first','second','third']}]

I need to have above array to be like this:

[
[{ a:'ai', b:'bi', c:['first','second','third'], cSplit:'first'}],
[{ a:'ai', b:'bi', c:['first','second','third'], cSplit:'second'}],
[{ a:'ai', b:'bi', c:['first','second','third'], cSplit:'third'}]
]

I tried this code:

var array = [{ a:'ai', b:'bi', c:['first','second','third']}]
var newArr = [];

for( var i=0; i<array[0]['c'].length; i++ ){
    var innerArr = array;
    innerArr[0]['cSplit'] = array[0]['c'][i];
    newArr.push(innerArr);
}

console.log('newArr', newArr)

But it shows:

[
[{a: "ai", b: "bi", c: ['first','second','third'] , cSplit: "third"}],
[{a: "ai", b: "bi", c: ['first','second','third'] , cSplit: "third"}],
[{a: "ai", b: "bi", c: ['first','second','third'] , cSplit: "third"}]
]

Why cSplit doesn't get the first and second value?

The problem is that you're mutating the same object, which is array[0]. — Axnyff
– Axnyff, Commented Jul 28, 2020 at 19:05

AlexAV-dev · Accepted Answer · 2020-07-28 19:02:34Z

1

let array = [{ a:'ai', b:'bi', c:['first','second','third']}]

let newArr = [];
for(let i = 0; i < array[0]['c'].length; i++ ) {
    newArr.push({ ...array[0], cSplit: array[0].c[i] })
}

console.log(newArr)

answered Jul 28, 2020 at 19:02

AlexAV-dev

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Comments

Yves Kipondo · Accepted Answer · 2020-07-28 19:04:27Z

1

Try with this code

var array = [{ a:'ai', b:'bi', c:['first','second','third']}]

let result = array[0].c.reduce((acc, current) => {
  return acc.concat({...array[0], csplit: current})
}, [])

console.log(result);

answered Jul 28, 2020 at 19:04

Yves Kipondo

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6 Comments

Axnyff Over a year ago

It looks like you're using reduce to do a map.

Yves Kipondo Over a year ago

I use reduce to create a completely new array instead of updating the existing one

Axnyff Over a year ago

map does not mutate either

Yves Kipondo Over a year ago

map will return a new array of course, as the array on which the map should be perform is the value of array[0].c to have access to all the value. if You perform map on the value of array directly you'll have access to one item which is an Object and not first, second and first

Axnyff Over a year ago

array[0].c.map(current => ({...array[0], csplit: current}) )

|

Sven.hig · Accepted Answer · 2020-07-28 19:14:25Z

1

A different approach using map

var array = [{ a:'ai', b:'bi', c:['first','second','third']}]
   
var res = array.map((o)=>{return Object.values(o)[2].map(e => {
var newob = {...o}
newob.cSplit = e
  return newob
  })   
})
    console.log(res)

edited Jul 28, 2020 at 19:14

answered Jul 28, 2020 at 19:11

Sven.hig

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Comments

tony19 · Accepted Answer · 2020-07-28 19:14:28Z

1

This can be succinctly done with Array.prototype.map:

const array = [{ a:'ai', b:'bi', c:['first','second','third']}]
const result = array[0].c.map(c => [{...array[0], cSplit: c}])
console.log(result)

answered Jul 28, 2020 at 19:14

tony19

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