Node.js / npm - anyway to tell if a package is pure JS or not?

Question

I've noticed that in trying to get seemingly simple node packages to install with npm (e.g. nerve, a "micro-framework") I often run into some form of dependency pain. After some digging, I tracked down the problem with nerve to the bcrypt module, which is apparently written in C/C++ and has to be compiled after the package manager downloads it.

Unfortunately, it seems like if you want this to work on Windows, the answer is (from one of the bcrypt issues threads) "install a Linux VM". So earlier today I did just that, and started running into other dependencies (you need certain unnamed apt packages installed before you can even think about building, despite GCC being installed), then eventually after seeing yet another C compiler error (about some package or other not being able to find "Arrays.c" I think), I actually gave up, and switched from nerve to express instead. Ironically, the larger and more complicated express installs with npm on Linux and Windows without a single issue.

So, my question is: is there any filter / dependency tracking available that lets you see if a package has additional dependencies besides node core? Because to me the allure of node is "everything in Javascript", and this kind of stuff dispels the illusion quite unpleasantly. In fact, despite having done more than my time working with C/C++, whenever I see a requirement to "make" something these days I generally run in the other direction screaming. :)

Answer 1

The first solution doesn't tell you if a dependency makes the package impure or not. Much better to search for gyp generated output:

find node_modules/ | grep binding.gyp || echo pure

Answer 2

Look out for the "scripts" field in the package.json.

If it contains something like

 "scripts": {
    "install": "make build",
 }

and a Makefile in the root directory, there's a good possibility that the package has some native module which would have to be compiled and built. Many packages include a Makefile only to compile tests.

This check on the package documents does not exclude the possibility that some dependency will have to be compiled and built. That would mean repeating this process for each dependency in the package.json, their dependencies and so on.

That said many modules have been updated to install, without build on Windows, express for one. However that cannot be assured of all packages.

Using a Linux VM seems to be the best alternative. Developing Node.js applications on Window gives you step by step instructions on installing a VM, Node.js and Express.