IJavascript provides a Javascript kernel for the Jupyter
project. Its code is currently split into 3 npm
packages: ijavascript,
nel and
jmp.
IJavascript provides the command, ijs, which is a link to bin/ijavascript.js
and is used to install the Javascript kernel and invoke the Jupyter notebook.
The Javascript kernel is implemented in lib/kernel.js by means of the Kernel
class. The CoffeeScript kernel,
jp-coffeescript, and the Babel
kernel, jp-babel, share a significant
amount of the code with lib/kernel.js. To facilitate the reuse of this shared
code, the Kernel class will be moved into its own npm package in the near
future.
The Kernel class depends on the npm packages, nel and jmp.
The nel package defines Session, a class that upon instantiation starts a
small Node.js server, lib/nel_server.js. The Session instance and
lib/nel_server.js communicate by means of an IPC channel. The Session
instance sends lib/nel_server.js three strings per request: action, code
and id. action is a string that determines the type of request: execution,
completion or inspection. code is a string with the Javascript code to be
executed, completed or inspected. And id is a string that identifies the
request. lib/nel_server.js responds to the request with either a
SuccessResult or
an ErrorResult.
Each response contains the property id set to the request id, so that the
Session instance can invoke the callbacks associated with the request.
The interface between the classes Kernel and Session is documented
here.
The jmp package is wrapper around the package node-zmq that transparently
encodes/decodes Jupyter-protocol messages over a ZMQ socket. See the
JSDoc-generated documentation here for further
details.