Fix broken typescript-checkJS script

[aweebit]

Problem

Currently, npm run typescript-checkJS results in

error TS6053: File 'lib/*.js' not found.
  The file is in the program because:
    Root file specified for compilation

on Windows (even when run from Git Bash), and in normal termination with no output even when there are type errors in the files on Linux and macOS.

Solution

Fix the script command.

The configuration for the JS check has been moved to a dedicated config file.

The script has been renamed to typescript-checkJs for better consistency with the TSConfig option name. (The script has been broken for a long time without someone noticing, so it is safe to assume it is not used in any contributors' custom scripts, and so the rename won't break anything.)

Peer PRs

…building upon this one

• Fix broken typescript-checkJS script. Store config for the script in jsconfig.json so that it is picked up by VS Code #1962

[aweebit]

Enough rebases, should be good to go now.

[shadowspawn]

The script runs fine on Mac, I use it as part of npm run test-all. I expect the underlying problem is it is relying on wildcard expansion by shell.

% npm run typescript-checkJS

> [email protected] typescript-checkJS
> tsc --allowJS --checkJS index.js lib/*.js --noEmit

% echo $?
0

[aweebit]

The script runs fine on Mac, I use it as part of npm run test-all. I expect the underlying problem is it is relying on wildcard expansion by shell.

% npm run typescript-checkJS

> [email protected] typescript-checkJS
> tsc --allowJS --checkJS index.js lib/*.js --noEmit

% echo $?
0

Checked it on Debian and the result was the same as what you get.

However, it isn't correct. There are currently a lot of type errors in the code and we are supposed to see them, instead we see nothing.

[aweebit]

Even when running the command for one individual file that has type errors (a lot of them) and with the exact option names from TypeScript's documentation, it still doesn't output anything:

$ npx tsc --allowJs --checkJs lib/command.js --noEmit
$ echo $?
0

So the command has been misleading the entire time even if it has been in use, so renaming it might not be a good idea.

[aweebit]

Good read: Why you should always quote your globs in NPM scripts

[shadowspawn]

There are (at least!) 3 different things going on:

• // @ts-check only works as the first line of the file
• lib/*.js in run-script typescript-checkJS does not work on Windows
• run-script typescript-checkJS generates far less errors than when enable checking in VSCode editor

The command-line help gives one clue, specifying the files apparently uses the default compiler options:

tsc app.ts util.ts
  Ignoring tsconfig.json, compiles the specified files with default compiler options.

I haven't yet managed to get VSCode to do the gentler type checking that typescript-checkJS implicitly uses, but it may just be difference between tsconfig.json and default compiler settings.

[shadowspawn]

Managed to get looser checks matching run-script in VSCode with both of these in tsconfig, so at least reproducible behaviour now:

   "checkJs": true,
   "strict": false, 

[aweebit]

Closing in favor of #1969.