make dataloader work in the browser

[jeffreyyoung]

Not sure if this is the best way to implement this feature. But I thought it'd be nice to be able to use DataLoader in the browser

[coveralls]

Coverage remained the same at 100.0% when pulling ab46ff5 on jeffreyyoung:master into dc3f0cd on facebook:master.

[timsuchanek]

This would be really awesome as client-side requests could be cached/batched

[Vanuan]

@leebyron any chance to merge it?
What's missing from this pull request?
Do you prefer to use something like this https://github.com/michaelrhodes/iso-next-tick ?

[Vanuan]

Hm... It looks like I it can be easily solved by some change in webpack config

[Compulsed]

It would be awesome for this to work in the browser, in the mean time does anyone know any alternatives?

[jeffreyyoung]

@Compulsed an alternative if you want to use the library in the browser now, is just fork the library, and replace process.nextTick with setTimeout in this file https://github.com/facebook/dataloader/blob/master/src/index.js#L212

[Vanuan]

Doesn't webpack already implement process.nextTick?

[marvinhagemeister]

Personally, I'd simply inline the check for node here. The overhead of a complete Environment class seems rather heavy to me. Most runtimes I can think of at the moment support setTimeout so we'd only have to check for node.

Something like this would suffice in my opinion. That way the code and performance impact is guaranteed to be trivial:

resolvedPromise.then(() => {
  if (process !== undefined && process.nextTick !== undefined) {
    process.nextTick(fn);
  } else {
    setTimeout(fn);
  }
});

(Note though that I'm not a contributor to dataloader. The core members probably have their reasons)

[jeffreyyoung]

Yeah That makes sense to me. I initially thought to do it that way, but wasn't quite sure how to get 100% test coverage. Do you know how i could get this logic process !== undefined && process.nextTick !== undefined to return false in the tests?