6 ways to generate a fibonacci sequence in JavaScript
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README.md

Fib-it

Fibonacci sequence implemented in 6 different ways with JavaScript. A nice excuse to explore functions, iterators, generators, iterable values, event emitters and streams!

npm version CircleCI JavaScript Style Guide

Install

As usual, npm-it-away:

npm i --save fib-it

Usage

The library exposes 6 different implementations of the fibonacci sequence.

The sequence will be infinite (as much as it can be considering JavaScript integer space) unless limited to max number.

Function-based implementation

const { genFib } = require('fib-it')

const f = genFib(6) // limit the sequence to numbers below 6
f() // 1
f() // 1
f() // 2
f() // 3
f() // 5
f() // null
f() // null

itarator-based implementation

const { genFibIterator } = require('fib-it')

it = genFibIterator(6) // { next: [Function: next] }
it.next() // { value: 1, done: false }
it.next() // { value: 1, done: false }
it.next() // { value: 2, done: false }
it.next() // { value: 3, done: false }
it.next() // { value: 5, done: false }
it.next() // { value: null, done: true }

// or

it = genFibIterator(6)
let result = it.next()
while (!result.done) {
  console.log(result.value)
  result = it.next()
}
// 1
// 1
// 2
// 3
// 5

generator-based implementation

gen = fibGenerator(6) // {}
gen.next() // { value: 1, done: false }
gen.next() // { value: 1, done: false }
gen.next() // { value: 2, done: false }
gen.next() // { value: 3, done: false }
gen.next() // { value: 5, done: false }
gen.next() // { value: null, done: true }
gen.next() // { value: undefined, done: true }

// or

gen = fibGenerator(6)
[...gen] // [ 1, 1, 2, 3, 5 ]

iterable-based implementation

const { genFibIterable } = require('fib-it')

it = genFibIterable(6) // { [Symbol(Symbol.iterator)]: [GeneratorFunction: [Symbol.iterator]] }
[...it] // [ 1, 1, 2, 3, 5 ]

// or

for (n of f) { console.log(n) }
// 1
// 1
// 2
// 3
// 5

event-emitter-based implementation

const { FibEmitter } = require('fib-it')

const fe = new FibEmitter(6, 10)
fe.on('data', n => console.log(n))
fe.on('end', () => console.log('done!'))
fe.start()
// 1
// 1
// 2
// 3
// 5
// done!

stream-based implementation

const s = new FibStream(7) // FibStream { ... }
s.on('data', chunk => console.log(chunk.readUInt32LE(0).toString()))
s.on('end', () => console.log('done!'))
// 1
// 1
// 2
// 3
// 5
// done!

When do I really use this?

There are some actual use cases for the fibonacci sequence. So maybe you need something like this in your code!

In reality this is just an experiment to compare different methodology to generate data sequences in JavaScript, so I expect it to be used mostly for education purposes rather than for production code.

Also with this goal in mind, the code is kept relatively simple and it's not meant to be feature-complete or error-proof.

Contribute

Feel more than welcome to report bugs or propose changes.

License

Licensed under MIT.