Do not copy devDependencies into the packaged app, prior to the prune step

[mhagmajer]

My dev dependencies are quite large (babel alone is over 300MB). The electron-packager analyses all those files which causes the build time to take a long time. I ended up explicitly ignoring all node modules that I want:

--ignore='^/node_modules/(?!(invariant|mongodb))'

Why not make it the default behaviour of electron-package to ignore dev dependencies?

[malept]

Thanks for the feature request, this is a duplicate of #35 (making --prune default).

[mhagmajer]

@malept, I don't think these are the same issues. The problem that I have is that electron-packager looks at all the modules that are in my devDependencies which take a lot of time given their size. Adding --prune flag doesn't help it. I was only able to mitigate that problem by adding the ignore flag mentoned above.

[malept]

(I edited the issues so that the comment from #35 is here, as that's where it's relevant.)

I don't think these are the same issues. [...]

Fair enough. I can't think of a good reason to not ignore devDependencies. Feel free to create a PR to change the behavior. You may have some trouble now that NPM 3 has a flat node_modules folder.

[malept]

See also: #235

[malept]

I saw a really poor implementation of this the other day. I believe the correct way to do it is something like this (pseudocode):

let package = require('./package.json');

// calculateDependencyTree returns a flat list of versioned dependencies, including
// sub-dependencies, for a given list of packages.
dependenciesToExclude() {
  let dependencies = calculateDependencyTree(package.dependencies);
  let devDependencies = calculateDependencyTree(package.devDependencies);
  return devDependencies - dependencies;
}

Ideally, this implementation does not depend on npm proper, because there have been at least two feature requests to be able to use alternative package managers.

[MarshallOfSound]

This should be possible soon MarshallOfSound/pruner#1