What are collapse() and combine() methods in Collect.js?

Collect.js - Interview Questions

collapse() : The collapse() method collapses a collection of arrays into a single, flat collection :

const collection = collect([[1], [{}, 5, {}], ['xoxo']]);

const collapsed = collection.collapse();

collapsed.all();

// [1, {}, 5, {}, 'xoxo']

const collection = collect([[1, 2, 3], [4, 5, 6], [7, 8, 9]]);

const collapsed = collection.collapse();

collapsed.all();

// [1, 2, 3, 4, 5, 6, 7, 8, 9]

combine() : The combine() method combines the keys of the collection with the values of another array or collection :

const collection = collect(['name', 'number']);

const combine = collection.combine(['Free Time Learn', 12]);

combine.all();

// {
//   name: 'Free Time Learn',
//   number: 12
// }