Add an interactive CLI to npm start

[keyz]

Implements #55.

Known issues:

• opn only opens applications (like Atom.app) but not binary executables in $PATH. To be specific, an user can't use edit vim unless there exists a Vim.app. To support that we'll need to use something like exec that picks up stuff from $PATH.

Demo:

Available commands: help, open (o), edit (e), verbose (v), exit

  Commands:

    help [command...]  Provides help for a given command.
    exit               Exits application.
    open               Opens your app in browser.
    edit [editor...]   Opens your app in editor. Defaults to `$EDITOR`; pass an extra string to specify your editor of choice
                       (e.g., `edit sublime text` or `e visual studio code`).
    verbose            Verbose mode (show all webpack logs).

cc @vjeux @gaearon

[gaearon]

Ooh, very neat! I’m not sure about the exact set of commands but I like the flow.
Would be great to continue brainstorming how else we could use this.

[SpencerCDixon]

What happens if there's a webpak compilation error? Will that get displayed still or does Vorpal hide that from users? As cool as this is there is a lot of value in seeing the explicit webpack bundles being built in the development process. Thoughts?

[keyz]

@SpencerCDixon it will still get displayed. This CLI doesn't "hide" anything. Moreover, you can turn on the verbose mode to show all raw webpack logs (although we're still deciding on if we want this feature).

[gaearon]

I wouldn’t want to allow verbose logs unless people actually start reporting weird crashes in loaders.
I’m more interested in this feature for some sort of rapid interaction. (REPL? 😄 )

[keyz]

oh like babel-node but actually executes in browser? woooooo

[SpencerCDixon]

Wow that's a sweet idea @gaearon, almost like a rails console. And sounds good @keyanzhang just wanted to confirm :)

[dthree]

Sounds awesome. If interested in using Vorpal for building the interactivity in the CLI, feel free to ask me any questions.

[gaearon]

A few more ideas:

• Toggle running tests on and off
• When linting errors are displayed, offer autofixing them (for the rules that have that options)

[dthree]

We can use vorpal.parse(process.argv) to jump straight into a command if extra args are passed into npm start.

Reference on vorpal.parse.

[gaearon]

I’m going to close this for now since it’s getting stale.
But! I’d like to reconsider this in the close future, for these two use cases:

• Doing the -u of Jest tests inline in the test watch mode.
• Doing the -f of ESLint inline in the regular mode.

Since Jest support is merged now, if this PR is resubmitted, I’d like to see it with at least one of these two features.