How to implement this code? How to make such functions? (this code cannot be changed)

  • friends - an array of objects
  • select, filterIn - functions that result in the work on the friends collection

Here's how friends put in the select and filterIn functions

var bestFriends = lib.query( friends, lib.select('name', 'gender', 'email'), lib.filterIn('favoriteFruit', ['Яблоко', 'Картофель']) );

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1 answer 1

select, filterIn - functions that result in the work on the friends collection

Not certainly in that way. The .select() and .filterIn() functions are functions that will result in functions that will work on the friends collection.

The function .query() gets an input

  • friends collection
  • the function to select fields from the friends collection, obtained as a result of lib.select('name', 'gender', 'email')
  • filtering items from the friends collection from lib.filterIn('favoriteFruit', ['Яблоко', 'Картофель'])

Sample Code

 var lib = { query: function (data, select, filter) { return select(filter(data)) }, select: function (...fields) { return function (data) { return data.map(function (x) { var item = {} fields.forEach(function (field) { item[field] = x[field] }) return item }) } }, filterIn: function (field, values) { return function (data) { return data.filter(function (x) { return values.indexOf(x[field]) > -1 }) } } } var friends = [ { name: 'Михаил', gender: 'муж', email: 'mikhail@example.com', favoriteFruit: 'Тыква' }, { name: 'Алексей', gender: 'муж', email: 'aleksey@example.com', favoriteFruit: 'Дыня' }, { name: 'Федор', gender: 'муж', email: 'fedor@example.com', favoriteFruit: 'Яблоко' }, { name: 'Иван', gender: 'муж', email: 'ivan@example.com', favoriteFruit: 'Мандарин' }, { name: 'Петр', gender: 'муж', email: 'petr@example.com', favoriteFruit: 'Картофель' } ] var bestFriends = lib.query( friends, lib.select('name', 'gender', 'email'), lib.filterIn('favoriteFruit', ['Яблоко', 'Картофель']) ); console.log(bestFriends)