Angular make reducer from an Array

Question

I understand that for count an array in Angular with rxjs I use reduce, for example if I want count : [{id: 1, items: [10, 20, 30]}] I use the following code:

const item = from([{id: 1, items: [10, 20, 30]}]);
item.pipe(
  map(actions => actions.items),
  mergeAll(),
  reduce((acc, i) => acc + i, 0)
).subscribe(p => console.log('Print 60: ', p));

The questions is How get make a reducer in the following array:

const items = [
{
  id: 1,
  boxing: [1, 2, 2]
},
{
  id: 2,
  boxing: [10, 10, 20]
}];

result expected:

[{
  id: 1,
  boxing: 5
},
{
  id: 2,
  boxing: 40
}]

I will appreciate your help

Any reason you're doing it inside of an rxjs stream? It seems since you have an array, you can just use the native .reduce function. — Jesse
– Jesse, Commented Jun 4, 2019 at 3:09
Hi jesse, no special reason, but the idea is to do it with rxjs. Thanks — lyonTypescript
– lyonTypescript, Commented Jun 4, 2019 at 3:24

Saksham · Accepted Answer · 2019-06-04 03:25:21Z

6

You can easily do this with javascript by using reduce and map as

const items = [
     {id: 1, boxing: [1, 2, 2]},
     {id: 2, boxing: [10, 10, 20]}
];

let reducedItems = items.map(val => {
  return {
    id: val.id,
    boxing: val.boxing.reduce((a, i) => a + i)
   }
});

console.log(reducedItems);

answered Jun 4, 2019 at 3:25

Saksham

9,4209 gold badges48 silver badges75 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Saksham Over a year ago

Alright @Jesse. I think you should post it as an answer

JossFD Over a year ago

stackblitz.com/edit/rxjs-cxhrt9 Just a small example applying @Saksham example inside the pipe map()

emkay · Accepted Answer · 2019-06-04 03:27:00Z

1

One approach can be this.

from(items).pipe(
  mergeMap((data) => from(data['boxing']).pipe(
    reduce((acc, x) => acc + x),
    map((val) => { data['boxing'] = val; return data })
  )),
  toArray()
).subscribe((val) => console.log(val));

answered Jun 4, 2019 at 3:27

emkay

8079 silver badges20 bronze badges

Collectives™ on Stack Overflow

Angular make reducer from an Array

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related