'use strict' const assert = require('chai').assert const D = require('derived') /* instantiate your data fundamentals -- or just begin from zero with `new D()` */ const data = new D({ '#1': { name: 'shangri-la', zipcode: 27498, inhabitants: [{ name: 'catherine', birthday: '11-17' }] }, '#2': { name: 'el dorado', zipcode: 69712, inhabitants: [{ name: 'pizarro', birthday: '04-01' }] }, '#3': { name: 'atlantis', zipcode: 18315, inhabitants: [{ name: 'plato', birthday: '07-18' }] }, '#4': { name: 'avalon', zipcode: 37851 } }) /* reindex the data on the go, for much faster and easy access later */ data.derived('cityId', (k, v) => [v.name, k]) /* now you can access it easily, no need for costly searches on independent index management */ assert.equal(data.cityId['shangri-la'], '#1') /* add data using super useful methods (you can't use normal methods, it's a Javascript limitation) */ let cityId = data.cityId data.push([cityId.avalon, 'inhabitants'], {name: 'arthur', birthday: '12-30'}) data.push([cityId.avalon, 'inhabitants'], {name: 'morgana', birthday: '12-31'}) /* create multiple derived indexes */ data.derived('personZip', function (cityId, cityData) { if (cityData.inhabitants) { cityData.inhabitants.forEach(person => { this.emit(person.name, cityData.zipcode) }) } }) /* no more `var personZip = zipcodesIndex[personsIndex[personId]]` or other verbose tricks access your data directly */ let personzip = data.personZip assert.equal(personzip['catherine'], 27498) assert.equal(personzip['arthur'], 37851) assert.equal(personzip['morgana'], 37851) /* indexes can be of anything (and they don't need names): */ let birthdaysByMonth = data.derived(function (_, city) { if (city.inhabitants) { city.inhabitants.forEach(person => { let month = parseInt(person.birthday.split('-')[0], 10) this.emit(month, person.name) }) } }) assert.deepEqual(birthdaysByMonth.getAll(12), ['arthur', 'morgana']) /* everything changes synchronously and automatically whenever you update the main data source */ data.set(`${cityId['atlantis']}.inhabitants.0.birthday`, '01-01') assert.equal(birthdaysByMonth[1], 'plato')