angular-multiton-reduce

An Angular 1.x model composed from a collection of dynamic multiton values

Installation

Requires browserify or similar npm-based build system.

In the command line:

npm install angular-multiton-reduce --save

In your angular composition define a variable and an associated reduce function:

angular.module('myModule', [])
  .factory('myUnion', require('angular-collective-boolean')(Array.prototype.some));

You may create as many angular entities as you like in this fashion.

Usage

Presuming a myUnion that reduces using Array.prototype.some per the example above.

Any property may be set on any instance at any time.

function fooController($scope, myUnion) {

  // get an instance with some key that represents this context
  var model = myUnion.getInstance('controller.foo');
  
  // set any property at any time
  model.myProperty = true;
  ...
  model.myProperty = false;
}

The collective value may be queried by invoking the injectable myUnion as a function and specifying the field name, in this case myProperty.

function barController($scope, myBoolean) {
  
  // scope property is true when any instance is true
  Object.defineProperty($scope, 'myProperty', {
    get: myUnion('myProperty')
  }
  
  // watch expression fires when any instance is true
  $scope.$watch(myUnion('myProperty'), function onChange(value) {
    console.log('union of all values has changed to', value);
  });
}

Reduce function

Every time the getter is invoked, the respective field is sampled across all instances and the result is collected into an Array. The Array is reduced using the reduceFn as callback.

A special case is made for Array.prototype.some and Array.prototype.every. These are invoked using the value Array as the invocation this.

The order of values in the Array is consistent with the order in which instances are created. All values are equal, there is no way to determine which value is from which instance.

Create function

An optional createFn may be supplied which will create the instance each time a unique getInstance() call is made.

The default createFn will create a simple Object.

Currently the createFn may not use angular injectables.

Limitations

Relies on angular change detection. There is no observable.