Add support for webpack configuration in TypeScript format

[jussikinnula]

To add support for webpack configuration in TypeScript format (e.g. webpack.config.ts), there's an existing package ts-node which just does the magic.

Webpack uses this method also internally, if specifying configuration file to webpack by using webpack --config webpack.config.ts. But since serverless-webpack does require the configuration by using a "require", ts-node needs to be required to support on-the-fly .ts -file requires.

[hassankhan]

Shouldn't we detect whether a TypeScript format configuration is being used before loading ts-node?

[HyperBrain]

I agree with @hassankhan . Unconditionally requiring ts-node and triggering all its side-effects maybe unwanted if you don't use TypeScript at all.
What about adding a command line switch --ts to conditionally enable TypeScript support on demand and initialize (require) it only then?

[hassankhan]

I was thinking of something more lo-fi like checking the file extension, either way sounds good 👍

[jussikinnula]

I originally had the require('ts-node/register'); conditionally, just before starting webpack compilation. So I'll update the PR next week when I'm back at work :-) ...

I wouldn't worry about any side effects, since ts-node actually does hook into require() and .ts -files. But of course it's a consideration always to add any extra dependencies.

[HyperBrain]

@jussikinnula Any update here?

[jussikinnula]

Updated version of the patch is now on top of latest upstream master!

I tested with my Angular starter project, and works (e.g. npm run sls:local):
https://github.com/jussikinnula/angular-serverless-typescript

[hassankhan]

Could these perhaps use Lodash's has() instead? Something like:

if (
_.has(this.serverless.service, 'custom.webpack') 
&& _.endsWith(this.serverless.service.custom.webpack, '.ts')
) {
...
}

[HyperBrain]

.. and lodash's _.endsWith() 😄

[hassankhan]

Updated the comment 😉

[hassankhan]

Aside from the one thing mentioned, this looks good to go! 👍

[jussikinnula]

I didn't want to add any extra dependencies besides ts-node, and also I tried to follow the coding style used elsewhere. If you want I can add lodash and use it's patterns, but I guess it would be a separate thing since similar if -clauses exist in various places under lib/.

[HyperBrain]

That's a valid point. We can do a "lodash"ification as a completely separate branch/PR and switch the code to use it everywhere, not only here. I will create a task for that, so that we get the whole codebase a bit leaner.
So this one is good to go.