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nicl -- Node.js Interactive Command Line


via npm

  • npm install nicl
  • Should be that simple.

from source

  • git clone git://
  • cd nicl
  • npm install

You may need to install fibers separately (npm install fibers).


Nicl helps you write a JavaScript interactive command-line application in the "classic" style using Node.js. By "classic" style, I mean a linear sequence of code that can ask the user for input and print results in the order it wants. This is easy by default in most programming languages, but it is hard in JavaScript, since its native environment (the browser) is not conducive to command-line aplications at all. And the de-facto standard for non-browser JavaScript is Node.js, allows command-line operation, but it is designed as an event-driven framework that doesn't in principle allow you to write sequential code interacting with the users. Nicl adds support for sequential interactive code running inside Node.js.

Many IDEs only understand "browser JavaScript" and "Node.js JavaScript". If you want to benefit from their advantages for your JavaScript project (autocompletion, debugging, etc...), your project had better be one of those two.

The main initial goal is educational. Using nicl and a free IDE like NetBeans, a beginner can start writing simple command-line applications in JavaScript, using code completion and the debugger, and complete many exercises until they understand variables, conditions, loops, function-calls, etc...


Here is a sample application using nicl to ask the user a couple questions and respond politely, in sequence:

var nicl = require("nicl");

function main() {
    nicl.printLine("Hello, what is your name?");
    var name = nicl.readLine();
    nicl.printLine("Great to meet you, " + name + "!");
    nicl.printLine("Where are you?");
    var place = nicl.readLine();
    nicl.printLine("Good. Hope it's all fine in " + place + "!");

Note how you need to run the code that uses nicl by calling and passing it the function to execute. Exiting the program needs to be done explicitly if so desired, as Node.js won't by default close the application until explicitly told to do so.


Nicl has been tested to work in OS X 10.10 Yosemite, both inside the NetBeans IDE console, and from the command line, by using node main.js to launch a program. Beware, it won't work properly inside the Node REPL, since the REPL sets input in "raw" mode (input processed at the keystroke level), and nicl is designed for cooked mode (linewise input).


Nicl builds on node-fibers by Marcel Laverdet, a coroutine-style library that allows adding suspension and resumption sematincs inside a single-threaded, event-driven library like Node.js, where blocking I/O is in principle not possible.


Support for raw input (keypress-level) will probably be added in the future.


(c) January 2016 Jon Beltran de Heredia (jonbho). Licensed under the GPL v2.0 license.


Node.js Interactive Command Line




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