What is .map and .reduce in angular 8 ?

Hi Siddharth,

.map() - You have received an array of containing multiple objects. You need only the id of each person

.reduce() - Just like .map , .reduce also runs callback for each element of an array

You need to sum the all year elements value for pilot array object . You can do it by .reduce like below

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Ravishankar N7y ago
Accepted answer
Hi Siddharth,

.map() - You have received an array of containing multiple objects. You need only the id of each person
// What you have
var officers = [
  { id: 20, name: 'Captain Piett' },
  { id: 24, name: 'General Veers' },
  { id: 56, name: 'Admiral Ozzel' },
  { id: 88, name: 'Commander Jerjerrod' }
];
// What you need
[20, 24, 56, 88]


let officersIds = officers.map(officer => officer.id);
.reduce() - Just like .map , .reduce also runs callback for each element of an array
var pilots = [
  {
    id: 10,
    name: "Poe Dameron",
    years: 14,
  },
  {
    id: 2,
    name: "Temmin 'Snap' Wexley",
    years: 30,
  },
  {
    id: 41,
    name: "Tallissan Lintra",
    years: 16,
  },
  {
    id: 99,
    name: "Ello Asty",
    years: 22,
  }
];
You need to sum the all year elements value for pilot array object . You can do it by .reduce like below
totalYears = pilots.reduce((acc, pilot) => acc + pilot.years, 0);
Aruljothy Sundaramoorthy7y ago
.Map - use the fetch the specific key value in an object of array... .Reduce - use the get some acuimulated or total value of an array..