collections-benchmarking

const ROUNDS = 1*5*1000;
let start;
const calls = new Map();
for(let i=0; i<10000; i++) {
  calls.set(Math.random().toString(), {request: {params: {fromOtherMaster: 'true'}}, instance: 'foo'})
}
const reduceIterableWith = (fn, initial, iterable) => {
  const iterator = iterable[Symbol.iterator]();
  let iterationResult,
    accumulator = initial;

  while ((iterationResult = iterator.next(), !iterationResult.done)) {
    accumulator = fn(accumulator, iterationResult.value);
  }
  return accumulator;
};
const filterIterableWith = (fn, iterable) => ({
  [Symbol.iterator]: () => {
    const iterator = iterable[Symbol.iterator]();

    return {
      next: () => {
        let {done, value} = iterator.next();
        while (!done && !fn(value)) {
          ({done, value} = iterator.next());
        }
        return {done, value};
      }
    }
  }
});
const mapIterableWith = (fn, iterable) => ({
  [Symbol.iterator]: () => {
    const iterator = iterable[Symbol.iterator]();
    return {
      next: () => {
        const {done, value} = iterator.next();
        return ({done, value: done ? undefined : fn(value)});
      }
    }
  }
});

start = new Date();
for(let i=0; i<ROUNDS; i++) {
  const sites = new Set()
  for(const call of calls.values()) {
    if(call.request.params.fromOtherMaster === 'true') {
      sites.add(call.request.instance);
    }
  }
  if(sites.size === 0) {
    console.log("never")
  }
}
console.log("for-of", new Date() - start)

start = new Date();
for(let i=0; i<ROUNDS; i++) {
  const sites = [...calls.values()].
    filter(call => call.request.params.fromOtherMaster === 'true').
    map(call => call.request.instance).
    reduce((sites, site) => sites.add(site), new Set());
  if(sites.size === 0) {
    console.log("never")
  }
}
console.log("functional", new Date() - start)

start = new Date();
for(let i=0; i<ROUNDS; i++) {
  const sites = [...calls.values()].
    reduce((sites, call) => {
      if(call.request.params.fromOtherMaster === 'true') {
        sites.add(call.request.instance);
      }
      return sites;
    }, new Set());
  if(sites.size === 0) {
    console.log("never")
  }
}
console.log("functional-reduce-only", new Date() - start)

start = new Date();
for(let i=0; i<ROUNDS; i++) {
  const sites = reduceIterableWith((sites, site) => sites.add(site), new Set(), mapIterableWith(call => call.request.instance, filterIterableWith(call => call.request.params.fromOtherMaster === 'true', calls.values())))
  if(sites.size === 0) {
    console.log("never")
  }
}
console.log("iterable-functional", new Date() - start)

start = new Date();
for(let i=0; i<ROUNDS; i++) {
  const sites = reduceIterableWith((sites, call) => {
    if(call.request.params.fromOtherMaster === 'true') {
      sites.add(call.request.instance);
    }
    return sites;
  }, new Set(), calls.values())
  if(sites.size === 0) {
    console.log("never")
  }
}
console.log("iterable-functional-reduce-only", new Date() - start)