the idea looks good to me. what are some usecases for this?

If you remember, we talked about this a few months ago. It's to enable the extension of the REPL functionality with 3rd third-party plugin. For example, a fuzzy search for files and tests, suspend mode, etc..

@MoLow wdyt?

@mikicho lets add it!
can you fix lint errors and add documentation?

@MoLow how to we want to declare on the plugins? like jest with a config file?

{
  "watchPlugins": [
    // default
    "jest-watch-suspend",
    // configure
    [
      "jest-watch-suspend", {
        // override key press
        "key": "s",
        // override prompt
        "prompt": "suspend watch mode",
        // starts in suspend mode
        "suspend-on-start": true
      }
    ]
  ]
}

@MoLow how to we want to declare on the plugins? like jest with a config file?

maybe we can simplify it to just be a map of { [key: path to plugin]: config object}?

@MoLow, I'm OK with whatever you prefer, but I think we might want to add more configurations in the future and it will be a breaking change.

I think we might want to add more configurations in the future and it will be a breaking change.

My suggestion was that each plugin can define its own schema for configuration. why would it be a breaking change?