Stroxy

A simple streaming wrapper for native event functions using ES2015 proxies.

Installation

npm i -S stroxy

Examples

Simple click handler

const doc = stroxy(document);
const clicks = doc.documentElement.addEventListener('click'); // or use .add('click'); shorthand
 
clicks.onValue(value => console.log('clicked in document'));

Click handler to get classnames

const doc = stroxy(document);
const clicks = doc
  .querySelectorAll('.link') // works on NodeLists as well!
  .addEventListener('click');
 
// Check if link is 'primary'
const isPrimary = clicks.pipe(e => (e.preventDefault(), e.target.className));
 
const listener = value => console.log('Classnames of clicked link:', value);
 
isPrimary.onValue(listener);

Remove value listener

clicks.offValue(listener);

Remove child stream

isPrimary.onValue will not be called anymore

doc
  .querySelectorAll('.link')
  .removeEventListener('click', clicks); // or use .remove('click', isPrimary);
// or explicitly
 
clicks.remove(isPrimary);

Remove handler

doc
  .querySelectorAll('.link')
  .removeEventListener('click', linkStream); // or use .remove('click', linkStream);

Stroxy API

Stroxy

stroxy(obj);

Returns a stroxified object on which certain methods (see Streamable Methods) return a stream.

stroxy.addStreamable(name, config);

Add a method signature that should be streamed.

name: The name of the method property config.callbackIndex: Which nth-parameter is the callback of the function config.type: Is it an event-adder or an event remover. Values: (stroxy.ADD|stroxy.REMOVE)

stroxy.addAlias(alias, name);

Add an Alias for a method signature. E.g. add is an alias for addEventListener.

alias: The shorthand name name: The streamable function name (has to be registered in the Streamable Methods as well)

Stream

Streams are created when invoking a Streamable Method. E.g. const intervalStream = stroxy(window).setInterval(400);

stream.pipe(fn);

Adds a function to the current stream. Pipes can be added to pipes. See Limitations about child streams though. The fn arguments will be what either the streamable function passes into the callback, or what the last pipe returns.

stream.onValue(fn);

Adds a listener function to the current stream or child stream to listen for changes.

stream.offValue(fn);

Remove a listener function from the current stream/child stream.

stream.remove(childStream);

Remove a child stream from the parent: Pipes and value listeners of the child stream will be unregistered.

Streamable Methods

Stroxy only works on certain methods and method signatures. Currently the following are supported:

• addEventListener (and add alias)
• removeEventListener (and remove alias)
• setTimeout
• clearTimeout
• setInterval
• clearInterval
• on (jQuery, EventEmitter)
• off (jQuery)
• removeListener (EventEmitter)

Limitations

Currently it isn't possible to create multiple children of child streams. Doing so will result in strange behavior:

const clicks = doc
  .querySelectorAll('.link') // works on NodeLists as well!
  .addEventListener('click'); // or use .add('click'); shorthand
 
const childStream = clicks.pipe(v => v);
 
childStream.pipe(w => w);
 
// Don't do this!
childStream.pipe(x => x);

Ideas to resolve to this issue are highly appreciated :)

Source of Inspiration

The whole concept is heavily inspired by bacon.js, although stroxy is a lot less versatile.

Special thanks to @gianlucaguarini for the inspiration.

Name

The name is a very bland combination of the words stream and proxy.