Developers get easily excited when something so used, acclaimed, and desired in another land comes to their own ... or the one they think they own ... This is the case of ECMAScript 6 Harmony Generators , something at this time you need to activate through the --harmony  flag in node  or going to about:flags  in Google Chrome Canary  url bar and enable experimental harmony/extension . Once you've done that, you'll be able, still through Chrome Canary  at this time, to test examples, benchmarks, and other things in this post ... ready? So here the first great news:  Generators Are Slower At least two times slower than forEach  and about 10 times slower than regular loops. This is the result showed in this jsperf benchmark  you can run too. Of course  generators are slower, there's a massive process behind each generator such: {   code: 'the generator function body',   context: 'the bound/trapped context',   scope: 'the whole scope used by the generator...