Ability to control a project scope

[s-panferov]

I've received several similar issues about how to control project scope.

#359
#351
#348
#330

It looks like that people want to typecheck only files directly included by an entry point. My opinion is that the loader should output the same errors as in direct tsc call.

I decided to conduct a small survey about the preferred default behavior:

1. Align with TypeScript and IDEs, check errors in files, specified by tsconfig.json and included from a resolution graph.

2. Don't align with TypeScript and IDEs, check errors in files from a resolution graph only. Ignore files from tsconfig.json

Please answer in comments and elaborate your position.

CC @johnnyreilly

[johnnyreilly]

I think aligning with tsc makes the most sense as it reduces the "distance" between tsc and working with webpack. Ideally I'd like any TypeScript loader to be a minimal difference from working with the compiler straight - focused on bundling alone pretty much. Also the loader can be simpler as a result. That said I understand the alternative point of view and understand to a certain extent. But if it becomes a feature of a loader then you're starting down the road of creating a codebase that has a tight coupling to that loader behaviour. Which is bad if you ever want to move away from webpack.

[johnnyreilly]

Oh and additionally: for tooling reasons. I want to see the same output in VSCode / atom / brackets etc as I do from webpack. Otherwise I have to code with red squigglies and learn to ignore them - which is a nasty development experience.

[colinskow]

The default should remain unchanged tsconfig.json (otherwise we risk breaking lots of builds.)

However I would also like loader options to support the following scenarios:'

1. Load entry files only
2. Load entry files, plus a custom list of additional files

Since I haven't figured out how to pass a virtual tsconfig.json to ATL I wrote a plugin that writes a custom config file for each build. But this is not ideal. I would like to pass in options without having to write a config file.

I propose the following two configuration options:

{
  entriesOnly: true, // default false
  additionalFiles: ['src/app/app.module.ts'] // only parsed when entriesOnly is true
}

These options simply generate a files array which is passed in with the tsconfig object to the compiler.

[colinskow]

Some background on my use case:

I have an Electron project with separate builds for main and renderer processes, as well as e2e tests and unit tests in TypeScript. They have conflicting Typings, so I get errors unless I am able to restrict type checking to the resolution graph.

With Angular 2, lazy loaded modules don't show up in the dependency graph, so it is necessary to specify those files in addition to entry points.

Since my project has lots of .ts files which aren't part of the main build, restricting the type checking makes builds run quite a bit faster.

[johnnyreilly]

Has anyone raised an issue with the TypeScript team itself to implement this behaviour in tsc? If they did implement then I would naturally be in favour of supporting this. Likewise if there's a reason they've chosen not to that could well be relevant. Is anyone aware of any discussion on the topic?

[johnnyreilly]

TypeStrong/ts-loader#267

[Llorx]

I'm with @colinskow. Having both options will be the perfect thing.

[colinskow]

@johnnyreilly TypeScript has implemented this behavior, but you have to specifically specify the entry files in the files array in your tsconfig.json. What I am asking for is the ability to pass this to the loader as an object in memory rather than writing a config file to disk.

[johnnyreilly]

@colinskow are you sure that's correct? My understanding was that if you are going to specify files then you're required to specify everything in project scope. So import or require statements do not contribute to project scope. Also, each entry represents an isolated scope and the tsconfig.json files does not indicate isolated scopes at all.

[colinskow]

@johnnyreilly you can test that out for yourself. Specify one entry file in the files array in your tsconfig.json and it will compile everything in the dependency tree, but will ignore all files outside the dependency tree.

Checkout my personal setup here:
https://github.com/colinskow/angular-electron-dream-starter/blob/master/config/webpack.common.js#L44