slim-observer

Javascript (typescript) implementation of observer pattern on less then 100 rows. It provides just o few most common functions and minified version is smaller then 2kB.

Installation

slim-observer is available on NPM and Bower. To install it, type:

$ npm install slim-observer

or

$ bower install slim-observer

Usage

You can also use it within the browser; install via npm/bower and use the slim-observer.min.js file found within the download. For example:

<script src="./node_modules/slim-observer/dist/slim-observer.min.js"></script>
<script>
    var observable = new SlimObserver.Subject();
    ...
</script> 

See full example in example.html

Functions

Basic usage

// create observable subject
var observable = new SlimObserver.Subject();
 
// create first listener
observable.subscribe(function(newValue){
    alert(newValue);
});
 
// create second listener
observable.subscribe(function(newValue){
    console.log(newValue);
});
 
observable.next('hello'); // emit value to all listeners
observable.next('world'); // emit another value

Get last emitted value

observable.getLast();

Create subject with initial value

var observable = new SlimObserver.Subject('initial value');

New subscriber with all history values replay.

observable.replayAndSubscribe(function(newValue){
    console.log(newValue);
});

Unsubscribe existing listener.

var observable = new SlimObserver.Subject();
 
var subscriber = observable.subscribe(function(newValue){
   alert(newValue);
});
 
subscriber.unsubscribe();

Emitting only unique values (if new value is different).

observable.nextUnique(123).nextUnique(123); // emits value to subscribers only once

Building tools

Build

Transpile TS code to JS in dist/ folder. Maps included.

npm run build

Unit Test

Tests framework used are: mocha & chai.

npm test

Testing with coverage:

nyc npm test

License

This project seed is licensed as Public Domain. Therefore, do whatever you want including changing the license for your needs in your project. More specifically, it was licensed as CC0 (Creative Commons 0) to further improve the freedom of a Public Domain Licence in context where it is not applicable.