Interact

Interactive node console, extended.

An interactive node console with auto-import, source reload, support for promises.

Installation

npm install @leonardvandriel/interact --save-dev

Create a configuration file console in the project root with content:

#!/usr/bin/env node
const interact = require('@leonardvandriel/interact')
interact.start()

Getting started

Start the console:

node console

Now run any node code:

> 1 + 1

Te result can be referred to with _:

> _ + 1

After making changes to the source, we can reload without restarting the console:

> .reload

NB: this reloads the sources referenced in module, but does not reload the configuration in the console file.

To get more details on the current configuration:

> .config

And for more in-console help:

> .help

All configuration is passed upon invoking interact.start(..) from console file:

const config = {}
config.useColor = true
interact.start(config)

More options can be found in the example console file. Internally we use Node's REPL module.

Import and reload

To import (require) modules, add module to the configuration:

const config = { module: {} }
config.module.fs = 'fs'
config.module.myclass = './lib/myclass'

After restarting (not reloading) the console, fs is available:

> fs.readFileSync('LICENSE', 'utf8')
> myclass.run()

When making changes to imported modules, a restart is not necessary. Instead we can reload the module:

> .reload
> .r

Perhaps there is additional informat that we want to make accessible in the REPL. This can be done by adding init to our configuration:

config.postInit = (context) => { context.myvar = 3 }

This variable is now accessible in the REPL:

> myvar
3

Reloading will delete the import cache and re-import the modules. Some modules contain state that will be lost after reloading. To persist module state, we can temporarily save it during the reloading:

config.preLoad = (context, temp) => { if (context.myclass) temp.database = context.myclass.database }
config.postLoad = (context, temp) => { if (temp.database) context.myclass.database = temp.database }

Promises

When evaluation results in a promise, this promise object is echoed instead of the result. We can capture all promises instead and await them:

config.capturePromise = true

This will assign an index to every promise and so it can be linked to the result later on:

> new Promise(r => setTimeout(r, 5000)).then(_ => 1234)
=> [1]

And 5 seconds later:

[1]: 1234

Often promises return almost immediately, which makes indexing unnecessary. To wait for 0.5 seconds, add to the configuration:

config.waitPromise = 500

Now simple promises are seamlessly evaluated:

> Promise.resolve(1234)
1234

History

The REPL history can be accessed with the up/down arrows. To persist this history across console runs, add to the configration:

config.historyLength = 100

This will store and reload history from the file .node_repl_history.

Make sure to add this path to .gitignore. History can also be store somewhere more centrally by changing the path:

config.historyFile = '/home/me/.node_repl_history'

Tests

npm test

License

Interact is licensed under the terms of the BSD 3-Clause License, see the included LICENSE file.

Authors

• Leo Vandriel