RxJS: map, filter, take, find, first, last and pluck. (https://codepen.io/raloliver/pen/vYBbwbM)

rxjs-list-operators.js

//altera a estrutura da entrada e transforma numa outra estrutura
var itemsMap = [{a: 1}, {a: 2}, {a: 3}, {a: 4},];
var sourceMap = Rx.Observable.from(items);
var subscriptionMap = source.map(x => { return {value: x.a} } ).subscribe(x => console.log(x));

//apenas os números pares retornam
var sourceFilter = Rx.Observable.from([1,2,3,4,5,6,7,8,9,10]);
var subscriptionFilter = source.filter(x => x % 2 === 0 ).subscribe(x => console.log(x));

//apenas um determinado número de elementos
var sourceTake = Rx.Observable.from([1,2,3,4,5,6,7,8,9,10]);
var subscriptionTake = source.take(3).subscribe(x => console.log(x))

//alguém com idade maior que 18
var peopleFind = [{name: 'Rick', age: 10},{name: 'Rose', age: 25},{name: 'Cassandra', age: 13},{name: 'Henry', age: 22}]
var sourceFind = Rx.Observable.from(people);
var subscriptionFind = source.find(x => x.age > 18).subscribe(x => console.log(x))

//primeiro elemento que passe na condição (nome que inicie com a letra R)
var peopleFirst = [{name: 'Rick', age: 10},{name: 'Rose', age: 25},{name: 'Cassandra', age: 13},{name: 'Henry', age: 22}]
var sourceFirst = Rx.Observable.from(people);
var subscriptionFirst = source.first(x => x.name[0] === 'R').subscribe(x => console.log(x))

//último elemento que passe na condição (nome que inicie com a letra R)
var peopleLast = [{name: 'Rick', age: 10},{name: 'Rose', age: 25},{name: 'Cassandra', age: 13},{name: 'Henry', age: 22}]
var sourceLast = Rx.Observable.from(people);
var subscriptionLast = source.last(x => x.name[0] === 'R').subscribe(x => console.log(x))

//retorna apenas os valores da propriedade selecionada
var peoplePluck = [{name: 'Rick', age: 10},{name: 'Rose', age: 25},{name: 'Cassandra', age: 13},{name: 'Henry', age: 22}]
var source = Rx.Observable.from(people);
var subscription = source.pluck('name').subscribe(x => console.log(x))