Insert bin prefix for script packages

Current Behavior

The output of index.js begins with use strict which if the package is intended to be a script, an error outputs.

Desired Behavior

When a package.json includes a bin parameter, prefix the index.js file with #!/usr/bin/env node

Who does this impact? Who is this for?

This is for users who wish to use tsdx for creating packages that are intended to be used in the command line.

Additional context

If it doesn’t make sense to base the behavior on the bin parameter in the package.json, it might make sense instead to make this a new template type, but it’s so similar to node, that this might be more effort than necessary.

[karlhorky]

We currently use TSDX to build Preflight, a command-line tool for the @upleveled students to check their project work before submitting.

The way that we’re dealing with it is to have a separate file in a bin folder, similar to the code below (although ours uses ES Modules):

#!/usr/bin/env node

'use strict';

require('../src/cli').run(process.argv.slice(2));

This is also how Prettier handles it - see also their package.json

Maybe this should be the recommendation from TSDX until there are other viable options?

[agilgur5]

So I’m working on a fix to this by making the dev/prod entry an actual Rollup plugin per https://github.com/formium/tsdx/issues/793#issuecomment-673952338 (it being out-of-band causes some issues like https://github.com/formium/tsdx/issues/351#issuecomment-657284291, also other folks could potentially use it) and recently had a breakthrough on how to make it work with multiple inputs (mostly by heavily reading the Rollup docs again, which I’ve been doing for upstream fixes in rollup-plugin-typescript2 like https://github.com/ezolenko/rollup-plugin-typescript2/pull/221 anyway). I feel pretty close but still need to do some testing, particularly against #367

In the meantime, here’s a one-liner workaround in Bash for this that one can use in a post-build script:

echo -e '#!/usr/bin/env node\n' "$(cat dist/index.js)" > dist/index.js