Collect.js mapToGroups() Method

The mapToGroups() method is used to iterate through the collection elements and passes each value of collection into the given callback function.

Syntax:

collect(array).mapToGroups(callback)

Parameters: The collect() method takes one argument that is converted into the collection and then mapToGroups() method is applied on it. The mapToGroups() method holds the callback function as a parameter.

Return Value: This method returns the collection elements according to given callback.

Below example illustrate the mapToGroups() method in collect.js:

Example 1:

Javascript

const collect = require('collect.js');

let obj = [{
    name: 'Ashok',
    score: 75
},
{
    name: 'Rakesh',
    score: 86
},
{
    name: 'Rajesh',
    score: 56
},
{
    name: 'Rakesh',
    score: 98
}];

const collection = collect(obj);

const sequence = collection.mapToGroups(
    (element) => [element.name, element.score])

console.log(sequence.all());

Output:

{ Ashok: [ 75 ], Rakesh: [ 86, 98 ], Rajesh: [ 56 ] }

Example 2:

Javascript

const collect = require('collect.js');

let obj = [
    {
        name: 'Rahul',
        dob: '25-10-96',
    },
    {
        name: 'Aditya',
        dob: '25-10-96',
    },
    {
        name: 'Abhishek',
        dob: '16-08-94',
    },
    {
        name: 'Rahul',
        dob: '25-10-96',
    },
];

const collection = collect(obj);

const sequence = collection.mapToGroups(
    (element) => [element.dob, element.name])

console.log(sequence.all());

Output:

{
  '25-10-96': [ 'Rahul', 'Aditya', 'Rahul' ],
  '16-08-94': [ 'Abhishek' ]
}