Ember.EventDispatcher Class packages/ember-views/lib/system/event_dispatcher.js:22

Adds an observer on a property.

This is the core method used to register an observer for a property.

Once you call this method, any time the key's value is set, your observer will be notified. Note that the observers are triggered any time the value is set, regardless of whether it has actually changed. Your observer should be prepared to handle that.

You can also pass an optional context parameter to this method. The context will be passed to your observer method whenever it is triggered. Note that if you add the same target/method pair on a key multiple times with different context parameters, your observer will only be called once with the last context you passed.

Observer Methods

Observer methods you pass should generally have the following signature if you do not pass a context parameter:

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fooDidChange: function(sender, key, value, rev) { };

The sender is the object that changed. The key is the property that changes. The value property is currently reserved and unused. The rev is the last property revision of the object when it changed, which you can use to detect if the key value has really changed or not.

If you pass a context parameter, the context will be passed before the revision like so:

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fooDidChange: function(sender, key, value, context, rev) { };

Usually you will not need the value, context or revision parameters at the end. In this case, it is common to write observer methods that take only a sender and key value as parameters or, if you aren't interested in any of these values, to write an observer that has no parameters at all.

Returns the cached value of a computed property, if it exists. This allows you to inspect the value of a computed property without accidentally invoking it if it is intended to be generated lazily.

Creates an instance of a class. Accepts either no arguments, or an object containing values to initialize the newly instantiated object with.

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App.Person = Ember.Object.extend({
  helloWorld: function() {
    alert("Hi, my name is " + this.get('name'));
  }
});

var tom = App.Person.create({
  name: 'Tom Dale'
});

tom.helloWorld(); // alerts "Hi, my name is Tom Dale".

create will call the init function if defined during Ember.AnyObject.extend

If no arguments are passed to create, it will not set values to the new instance during initialization:

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var noName = App.Person.create();
noName.helloWorld(); // alerts undefined

NOTE: For performance reasons, you cannot declare methods or computed properties during create. You should instead declare methods and computed properties when using extend.

Set the value of a property to the current value minus some amount.

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player.decrementProperty('lives');
orc.decrementProperty('health', 5);

Destroys an object by setting the isDestroyed flag and removing its metadata, which effectively destroys observers and bindings.

If you try to set a property on a destroyed object, an exception will be raised.

Note that destruction is scheduled for the end of the run loop and does not happen immediately. It will set an isDestroying flag immediately.

Creates a new subclass.

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App.Person = Ember.Object.extend({
  say: function(thing) {
    alert(thing);
   }
});

This defines a new subclass of Ember.Object: App.Person. It contains one method: say().

You can also create a subclass from any existing class by calling its extend() method. For example, you might want to create a subclass of Ember's built-in Ember.View class:

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App.PersonView = Ember.View.extend({
  tagName: 'li',
  classNameBindings: ['isAdministrator']
});

When defining a subclass, you can override methods but still access the implementation of your parent class by calling the special _super() method:

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App.Person = Ember.Object.extend({
  say: function(thing) {
    var name = this.get('name');
    alert(name + ' says: ' + thing);
  }
});

App.Soldier = App.Person.extend({
  say: function(thing) {
    this._super(thing + ", sir!");
  },
  march: function(numberOfHours) {
    alert(this.get('name') + ' marches for ' + numberOfHours + ' hours.');
  }
});

var yehuda = App.Soldier.create({
  name: "Yehuda Katz"
});

yehuda.say("Yes");  // alerts "Yehuda Katz says: Yes, sir!"

The create() on line #17 creates an instance of the App.Soldier class. The extend() on line #8 creates a subclass of App.Person. Any instance of the App.Person class will not have the march() method.

You can also pass Mixin classes to add additional properties to the subclass.

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App.Person = Ember.Object.extend({
  say: function(thing) {
    alert(this.get('name') + ' says: ' + thing);
  }
});

App.SingingMixin = Mixin.create({
  sing: function(thing){
    alert(this.get('name') + ' sings: la la la ' + thing);
  }
});

App.BroadwayStar = App.Person.extend(App.SingingMixin, {
  dance: function() {
    alert(this.get('name') + ' dances: tap tap tap tap ');
  }
});

The App.BroadwayStar class contains three methods: say(), sing(), and dance().

Retrieves the value of a property from the object.

This method is usually similar to using object[keyName] or object.keyName, however it supports both computed properties and the unknownProperty handler.

Because get unifies the syntax for accessing all these kinds of properties, it can make many refactorings easier, such as replacing a simple property with a computed property, or vice versa.

Computed Properties

Computed properties are methods defined with the property modifier declared at the end, such as:

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fullName: function() {
  return this.get('firstName') + ' ' + this.get('lastName');
}.property('firstName', 'lastName')

When you call get on a computed property, the function will be called and the return value will be returned instead of the function itself.

Unknown Properties

Likewise, if you try to call get on a property whose value is undefined, the unknownProperty() method will be called on the object. If this method returns any value other than undefined, it will be returned instead. This allows you to implement "virtual" properties that are not defined upfront.

To get the values of multiple properties at once, call getProperties with a list of strings or an array:

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record.getProperties('firstName', 'lastName', 'zipCode');
// { firstName: 'John', lastName: 'Doe', zipCode: '10011' }

is equivalent to:

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record.getProperties(['firstName', 'lastName', 'zipCode']);
// { firstName: 'John', lastName: 'Doe', zipCode: '10011' }

Retrieves the value of a property, or a default value in the case that the property returns undefined.

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person.getWithDefault('lastName', 'Doe');

Set the value of a property to the current value plus some amount.

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person.incrementProperty('age');
team.incrementProperty('score', 2);

An overridable method called when objects are instantiated. By default, does nothing unless it is overridden during class definition.

Example:

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App.Person = Ember.Object.extend({
  init: function() {
    alert('Name is ' + this.get('name'));
  }
});

var steve = App.Person.create({
  name: "Steve"
});

// alerts 'Name is Steve'.

NOTE: If you do override init for a framework class like Ember.View, be sure to call this._super(...arguments) in your init declaration! If you don't, Ember may not have an opportunity to do important setup work, and you'll see strange behavior in your application.

Convenience method to call propertyWillChange and propertyDidChange in succession.

Remove an observer you have previously registered on this object. Pass the same key, target, and method you passed to addObserver() and your target will no longer receive notifications.

Augments a constructor's prototype with additional properties and functions:

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MyObject = Ember.Object.extend({
  name: 'an object'
});

o = MyObject.create();
o.get('name'); // 'an object'

MyObject.reopen({
  say: function(msg){
    console.log(msg);
  }
})

o2 = MyObject.create();
o2.say("hello"); // logs "hello"

o.say("goodbye"); // logs "goodbye"

To add functions and properties to the constructor itself, see reopenClass

Augments a constructor's own properties and functions:

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MyObject = Ember.Object.extend({
  name: 'an object'
});

MyObject.reopenClass({
  canBuild: false
});

MyObject.canBuild; // false
o = MyObject.create();

In other words, this creates static properties and functions for the class. These are only available on the class and not on any instance of that class.

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App.Person = Ember.Object.extend({
  name : "",
  sayHello : function() {
    alert("Hello. My name is " + this.get('name'));
  }
});

App.Person.reopenClass({
  species : "Homo sapiens",
  createPerson: function(newPersonsName){
    return App.Person.create({
      name:newPersonsName
    });
  }
});

var tom = App.Person.create({
  name : "Tom Dale"
});
var yehuda = App.Person.createPerson("Yehuda Katz");

tom.sayHello(); // "Hello. My name is Tom Dale"
yehuda.sayHello(); // "Hello. My name is Yehuda Katz"
alert(App.Person.species); // "Homo sapiens"

Note that species and createPerson are not valid on the tom and yehuda variables. They are only valid on App.Person.

To add functions and properties to instances of a constructor by extending the constructor's prototype see reopen

Sets the provided key or path to the value.

This method is generally very similar to calling object[key] = value or object.key = value, except that it provides support for computed properties, the setUnknownProperty() method and property observers.

Computed Properties

If you try to set a value on a key that has a computed property handler defined (see the get() method for an example), then set() will call that method, passing both the value and key instead of simply changing the value itself. This is useful for those times when you need to implement a property that is composed of one or more member properties.

Unknown Properties

If you try to set a value on a key that is undefined in the target object, then the setUnknownProperty() handler will be called instead. This gives you an opportunity to implement complex "virtual" properties that are not predefined on the object. If setUnknownProperty() returns undefined, then set() will simply set the value on the object.

Property Observers

In addition to changing the property, set() will also register a property change with the object. Unless you have placed this call inside of a beginPropertyChanges() and endPropertyChanges(), any "local" observers (i.e. observer methods declared on the same object), will be called immediately. Any "remote" observers (i.e. observer methods declared on another object) will be placed in a queue and called at a later time in a coalesced manner.

Sets a list of properties at once. These properties are set inside a single beginPropertyChanges and endPropertyChanges batch, so observers will be buffered.

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record.setProperties({ firstName: 'Charles', lastName: 'Jolley' });

Returns a string representation which attempts to provide more information than Javascript's toString typically does, in a generic way for all Ember objects.

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App.Person = Em.Object.extend()
person = App.Person.create()
person.toString() //=> "<App.Person:ember1024>"

If the object's class is not defined on an Ember namespace, it will indicate it is a subclass of the registered superclass:

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Student = App.Person.extend()
student = Student.create()
student.toString() //=> "<(subclass of App.Person):ember1025>"

If the method toStringExtension is defined, its return value will be included in the output.

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App.Teacher = App.Person.extend({
  toStringExtension: function() {
    return this.get('fullName');
  }
});
teacher = App.Teacher.create()
teacher.toString(); //=> "<App.Teacher:ember1026:Tom Dale>"

Set the value of a boolean property to the opposite of its current value.

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starship.toggleProperty('warpDriveEngaged');

Override to implement teardown.