es6 generators

generator.js

require('console');
/**
 * Created by rober_000 on 5/12/2016.
 */
class Factorials{
    recursive(n){
        if (n === 1) {
            return 1;
        }
        return n * this.recursive(n - 1);
    }

    generative(n){
        var gf = this.inner_generative(n)
        var intermediate = gf.next();
        var final = NaN;
        while(!intermediate.done){
            // you could be doing work here, which is the purpose of a generator
            final = intermediate.value;
            intermediate = gf.next(); // next takes a value, but disposes of it. generators must maintain their own stack
        }
        return final;
    }
    *inner_generative(n){
        var sequence = [1]
        while (n-- > 0) {
            yield sequence[sequence.length - 1]
            sequence.push((sequence.length + 1) * sequence[sequence.length - 1])
        }
    }
}

f = new Factorials();
console.log(f.recursive(5));
console.log(f.generative(5));