map array to another array in TypeScript

Question

Can I improve my code and replace for-loop by array.map?

I searched and I think I could do that but I didn't find how could I apply that.

This is what I found :

var result = arr.map(person => ({ value: person.id, text: person.name }));

And my code is here:

  public getFlights(): Observable<RowItem[]> {
    return this.http
      .get(this.apiHostFlights)
      .map((res: any) => {
        return <LocationModelItem[]>res.json();
      })
      .map((items: LocationModelItem[]) => {
        var rowItems: RowItem[]=[];
        var cachedLenght = items.length;
        for (var i = 0; i < cachedLenght; i++) {
          rowItems.push(
            new RowItem(i, items[i].name, items[i].img, items[i].category)
          );
        }
        return rowItems;
      })
      .catch((error: any) => {
        return Observable.throw(error.statusText);
      });
  }

Thomas · Accepted Answer · 2018-03-06T10:13:09.607

11

 public getFlights(): Observable<RowItem[]> {
    return this.http
      .get(this.apiHostFlights)
      .map((res: any) => {
        return <LocationModelItem[]>res.json();
      })
      .map((items: LocationModelItem[]) => {
        return items.map((item, index) => ({
           index: index,
           name: item.name,
           img: item.img,
           category: item.category)
        }))

      })
      .catch((error: any) => {
        return Observable.throw(error.statusText);
      });
  }

This should do it hopefully

edited Mar 06 '18 at 10:13

answered Mar 06 '18 at 10:05

Thomas

2,431
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22

can I you made it like this answer var result = arr.map(person => ({ value: person.id, text: person.name })); – amorenew Mar 06 '18 at 10:08
That means you want to get a list of objects instead of a list of RowItems? – Thomas Mar 06 '18 at 10:11
I just want a better performance instead of using for loop or 3 maps but rowitems – amorenew Mar 06 '18 at 10:12
still I loop 3 times by using 3 maps – amorenew Mar 06 '18 at 10:16
1

Because you have to. I see no logical possibility to avoid that. – Thomas Mar 06 '18 at 10:18
1

@amorenew and "3 maps" is a problem because... ? – zerkms Mar 06 '18 at 10:46
As I understand map is like for loop so it is a performance issue – amorenew Mar 06 '18 at 11:20

map array to another array in TypeScript

1 Answers1