JS libraries that act "too" smartly in Node

[sjrd]

Some JavaScript libraries are "too" smart about how to behave depending on their environment. And typically on Node they behave as a Node module, which is not what we want.

See for example Mustache: https://groups.google.com/d/msg/scala-js/vk_FEuwCG78/EbWgUMlgF5kJ

[gzm0]

Hmmm... it is not clear at all to me how to solve this. For Mustache as an example, we'd have to write:

mustache = require(<filename>);

For libraries which are not "too" smart, we'd have to:

require(<filename>)

(or copy all the properties of the returned object to global).

The obvious problem is that we don't know which libraries are "too" smart and neither would we know the variable to assign their result to.

As tested last week, we also cannot undefined exports, since it is redefined in each required file again.

[lihaoyi]

Isn't

mustache = require(<filename>);

The "standard" (haha) for many javascript libraries using requireJS? I know I've seen a lot of things using that pattern (Ace editor, Doppio, ...), probably more than I've seen use the require-and-copy-properties-to-global pattern

[gzm0]

That's according to CommonJS. RequireJS (which also has a function require) allows for asynchronous loading and therefore probably more common in the browser.

However, the copy-to-global is implicitly used in browsers a lot when multiple <script> tags are used...

[lihaoyi]

Damnit javascript

[lihaoyi]

Is there any metadata that tells us whether its a CommonJS or RequireJS package? Presumably the node packages have some metadata? I can't imagine we're the only ones with this problem, but maybe javascript people are just used to manually doing everything.

I guess worst case fallback is we add another SBT thing

jsDependencies += requireJS("org.webjars" % "mustachejs" % "0.8.1" / "mustache.js" % "test")
jsDependencies += commonJS("org.webjars" % "mustachejs" % "0.8.1" / "mustache.js" % "test")
jsDependencies += dumpsInGlobals("org.webjars" % "mustachejs" % "0.8.1" / "mustache.js" % "test")

to disambiguate them? At least then someone can get bitten, figure it out, and then manually annotate the javascript dependencies as to how they behave...

[gzm0]

Well... this is the path of supporting every JavaScript module style... and I really didn't want to go there... :(

[gzm0]

And no, AFAIK there is no such metadata. Mustache tries to be smart and detect how it is loaded using dynamic checks (e.g. does the exports variable exist).

[gzm0]

We currently don't know how to solve this. Moving to 0.5.1.

[gzm0]

As discussed with @sjrd, we should just document to fall back on PhantomJS, if this happens, since we don't know how to solve this.

[lihaoyi]

Sounds good to me, not that the problems with phantomjs seem to have disappeared!