Class Ember.Set

An unordered collection of objects.

A Set works a bit like an array except that its items are not ordered. You can create a set to efficiently test for membership for an object. You can also iterate through a set just like an array, even accessing objects by index, however there is no guarantee as to their order.

All Sets are observable via the Enumerable Observer API - which works on any enumerable object including both Sets and Arrays.

Creating a Set

You can create a set like you would most objects using new Ember.Set(). Most new sets you create will be empty, but you can also initialize the set with some content by passing an array or other enumerable of objects to the constructor.

Finally, you can pass in an existing set and the set will be copied. You can also create a copy of a set by calling Ember.Set#copy().

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// creates a new empty set
var foundNames = new Ember.Set();

// creates a set with four names in it.
var names = new Ember.Set(["Charles", "Tom", "Juan", "Alex"]); // :P

// creates a copy of the names set.
var namesCopy = new Ember.Set(names);

// same as above.
var anotherNamesCopy = names.copy();

Adding/Removing Objects

You generally add or remove objects from a set using add() or remove(). You can add any type of object including primitives such as numbers, strings, and booleans.

Unlike arrays, objects can only exist one time in a set. If you call add() on a set with the same object multiple times, the object will only be added once. Likewise, calling remove() with the same object multiple times will remove the object the first time and have no effect on future calls until you add the object to the set again.

NOTE: You cannot add/remove null or undefined to a set. Any attempt to do so will be ignored.

In addition to add/remove you can also call push()/pop(). Push behaves just like add() but pop(), unlike remove() will pick an arbitrary object, remove it and return it. This is a good way to use a set as a job queue when you don't care which order the jobs are executed in.

Testing for an Object

To test for an object's presence in a set you simply call Ember.Set#contains().

Observing changes

When using Ember.Set, you can observe the "[]" property to be alerted whenever the content changes. You can also add an enumerable observer to the set to be notified of specific objects that are added and removed from the set. See Ember.Enumerable for more information on enumerables.

This is often unhelpful. If you are filtering sets of objects, for instance, it is very inefficient to re-filter all of the items each time the set changes. It would be better if you could just adjust the filtered set based on what was changed on the original set. The same issue applies to merging sets, as well.

Other Methods

Ember.Set primary implements other mixin APIs. For a complete reference on the methods you will use with Ember.Set, please consult these mixins. The most useful ones will be Ember.Enumerable and Ember.MutableEnumerable which implement most of the common iterator methods you are used to on Array.

Note that you can also use the Ember.Copyable and Ember.Freezable APIs on Ember.Set as well. Once a set is frozen it can no longer be modified. The benefit of this is that when you call frozenCopy() on it, Ember will avoid making copies of the set. This allows you to write code that can know with certainty when the underlying set data will or will not be modified.

Show:

Module: ember
obj
Object
The object to add.
returns
Ember.Set
The set itself.

Adds an object to the set. Only non-null objects can be added to a set and those can only be added once. If the object is already in the set or the passed value is null this method will have no effect.

This is an alias for Ember.MutableEnumerable.addObject().

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var colors = new Ember.Set();
colors.add("blue");     // ["blue"]
colors.add("blue");     // ["blue"]
colors.add("red");      // ["blue", "red"]
colors.add(null);       // ["blue", "red"]
colors.add(undefined);  // ["blue", "red"]
Module: ember
objects
Ember.Enumerable
the objects to add.
returns
Ember.Set
The set itself.

Adds each object in the passed enumerable to the set.

This is an alias of Ember.MutableEnumerable.addObjects()

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var colors = new Ember.Set();
colors.addEach(["red", "green", "blue"]);  // ["red", "green", "blue"]
Module: ember
target
Object
opts
Hash
returns
this

Registers an enumerable observer. Must implement Ember.EnumerableObserver mixin.

Module: ember
object
Object
The object to add to the enumerable.
returns
Object
the passed object

Required. You must implement this method to apply this mixin.

Attempts to add the passed object to the receiver if the object is not already present in the collection. If the object is present, this method has no effect.

If the passed object is of a type not supported by the receiver, then this method should raise an exception.

Module: ember
objects
Ember.Enumerable
the objects to add.
returns
Object
receiver

Adds each object in the passed enumerable to the receiver.

Module: ember
callback
Function
The callback to execute
target
Object
The target object to use
returns
Boolean
`true` if the passed function returns `true` for any item

Returns true if the passed function returns true for any item in the enumeration. This corresponds with the some() method in JavaScript 1.6.

The callback method you provide should have the following signature (all parameters are optional):

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function(item, index, enumerable);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • enumerable is the enumerable object itself.

It should return the true to include the item in the results, false otherwise.

Note that in addition to a callback, you can also pass an optional target object that will be set as this on the context. This is a good way to give your iterator function access to the current object.

Usage Example:

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if (people.any(isManager)) { Paychecks.addBiggerBonus(); }
Module: ember
key
String
the property to test
value
String
optional value to test against.
returns
Boolean
`true` if the passed function returns `true` for any item

Returns true if the passed property resolves to true for any item in the enumerable. This method is often simpler/faster than using a callback.

Module: ember
returns
Ember.Set
An empty Set

Clears the set. This is useful if you want to reuse an existing set without having to recreate it.

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var colors = new Ember.Set(["red", "green", "blue"]);
colors.length;  // 3
colors.clear();
colors.length;  // 0
Module: ember
returns
Array
the array without null and undefined elements.

Returns a copy of the array with all null and undefined elements removed.

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var arr = ["a", null, "c", undefined];
arr.compact();  // ["a", "c"]
Module: ember
obj
Object
The object to search for.
returns
Boolean
`true` if object is found in enumerable.

Returns true if the passed object can be found in the receiver. The default version will iterate through the enumerable until the object is found. You may want to override this with a more efficient version.

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var arr = ["a", "b", "c"];
arr.contains("a"); // true
arr.contains("z"); // false
Module: ember
deep
Boolean
if `true`, a deep copy of the object should be made
returns
Object
copy of receiver

Override to return a copy of the receiver. Default implementation raises an exception.

Module: ember
arguments

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 or use the createWithMixins shorthand.

Module: ember
arguments

Equivalent to doing extend(arguments).create(). If possible use the normal create method instead.

Module: ember
returns
Ember.Object
receiver

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.

Module: ember
callback
Function
binding
Object

Iterate over each computed property for the class, passing its name and any associated metadata (see metaForProperty) to the callback.

Module: ember
start
Number
optional start offset for the content change. For unordered enumerables, you should always pass -1.
removing
Ember.Enumerable|Number
An enumerable of the objects to be removed or the number of items to be removed.
adding
Ember.Enumerable|Number
An enumerable of the objects to be added or the number of items to be added.

Invoke this method when the contents of your enumerable has changed. This will notify any observers watching for content changes. If your are implementing an ordered enumerable (such as an array), also pass the start and end values where the content changed so that it can be used to notify range observers.

Module: ember
removing
Ember.Enumerable|Number
An enumerable of the objects to be removed or the number of items to be removed.
adding
Ember.Enumerable|Number
An enumerable of the objects to be added or the number of items to be added.

Invoke this method just before the contents of your enumerable will change. You can either omit the parameters completely or pass the objects to be removed or added if available or just a count.

Module: ember
callback
Function
The callback to execute
target
Object
The target object to use
returns
Boolean

Returns true if the passed function returns true for every item in the enumeration. This corresponds with the every() method in JavaScript 1.6.

The callback method you provide should have the following signature (all parameters are optional):

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function(item, index, enumerable);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • enumerable is the enumerable object itself.

It should return the true or false.

Note that in addition to a callback, you can also pass an optional target object that will be set as this on the context. This is a good way to give your iterator function access to the current object.

Example Usage:

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if (people.every(isEngineer)) { Paychecks.addBigBonus(); }
Module: ember
key
String
the property to test
value
String
optional value to test against.
returns
Boolean

Returns true if the passed property resolves to true for all items in the enumerable. This method is often simpler/faster than using a callback.

Module: ember
callback
Function
The callback to execute
target
Object
The target object to use
returns
Array
A filtered array.

Returns an array with all of the items in the enumeration that the passed function returns true for. This method corresponds to filter() defined in JavaScript 1.6.

The callback method you provide should have the following signature (all parameters are optional):

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function(item, index, enumerable);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • enumerable is the enumerable object itself.

It should return the true to include the item in the results, false otherwise.

Note that in addition to a callback, you can also pass an optional target object that will be set as this on the context. This is a good way to give your iterator function access to the current object.

Module: ember
key
String
the property to test
value
String
optional value to test against.
returns
Array
filtered array

Returns an array with just the items with the matched property. You can pass an optional second argument with the target value. Otherwise this will match any property that evaluates to true.

Module: ember
callback
Function
The callback to execute
target
Object
The target object to use
returns
Object
Found item or `undefined`.

Returns the first item in the array for which the callback returns true. This method works similar to the filter() method defined in JavaScript 1.6 except that it will stop working on the array once a match is found.

The callback method you provide should have the following signature (all parameters are optional):

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function(item, index, enumerable);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • enumerable is the enumerable object itself.

It should return the true to include the item in the results, false otherwise.

Note that in addition to a callback, you can also pass an optional target object that will be set as this on the context. This is a good way to give your iterator function access to the current object.

Module: ember
key
String
the property to test
value
String
optional value to test against.
returns
Object
found item or `undefined`

Returns the first item with a property matching the passed value. You can pass an optional second argument with the target value. Otherwise this will match any property that evaluates to true.

This method works much like the more generic find() method.

Module: ember
callback
Function
The callback to execute
target
Object
The target object to use
returns
Object
receiver

Iterates through the enumerable, calling the passed function on each item. This method corresponds to the forEach() method defined in JavaScript 1.6.

The callback method you provide should have the following signature (all parameters are optional):

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function(item, index, enumerable);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • enumerable is the enumerable object itself.

Note that in addition to a callback, you can also pass an optional target object that will be set as this on the context. This is a good way to give your iterator function access to the current object.

Module: ember
returns
Object
receiver

Freezes the object. Once this method has been called the object should no longer allow any properties to be edited.

Module: ember
returns
Object
copy of receiver or receiver

If the object implements Ember.Freezable, then this will return a new copy if the object is not frozen and the receiver if the object is frozen.

Raises an exception if you try to call this method on a object that does not support freezing.

You should use this method whenever you want a copy of a freezable object since a freezable object can simply return itself without actually consuming more memory.

Module: ember
key
String
name of the property
returns
Array
The mapped array.

Alias for mapBy

Module: ember

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() {
    this._super();
    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 or Ember.ArrayController, be sure to call this._super() 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.

Module: ember
methodName
String
the name of the method
args
Object...
optional arguments to pass as well.
returns
Array
return values from calling invoke.

Invokes the named method on every object in the receiver that implements it. This method corresponds to the implementation in Prototype 1.6.

Module: ember
obj
Ember.Set
the other object.
returns
Boolean

Returns true if the passed object is also an enumerable that contains the same objects as the receiver.

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var colors = ["red", "green", "blue"],
    same_colors = new Ember.Set(colors);

same_colors.isEqual(colors);               // true
same_colors.isEqual(["purple", "brown"]);  // false
Module: ember
callback
Function
The callback to execute
target
Object
The target object to use
returns
Array
The mapped array.

Maps all of the items in the enumeration to another value, returning a new array. This method corresponds to map() defined in JavaScript 1.6.

The callback method you provide should have the following signature (all parameters are optional):

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function(item, index, enumerable);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • enumerable is the enumerable object itself.

It should return the mapped value.

Note that in addition to a callback, you can also pass an optional target object that will be set as this on the context. This is a good way to give your iterator function access to the current object.

Module: ember
key
String
name of the property
returns
Array
The mapped array.

Similar to map, this specialized function returns the value of the named property on all items in the enumeration.

Module: ember
key
String
property name

In some cases, you may want to annotate computed properties with additional metadata about how they function or what values they operate on. For example, computed property functions may close over variables that are then no longer available for introspection.

You can pass a hash of these values to a computed property like this:

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person: function() {
  var personId = this.get('personId');
  return App.Person.create({ id: personId });
}.property().meta({ type: App.Person })

Once you've done this, you can retrieve the values saved to the computed property from your class like this:

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MyClass.metaForProperty('person');

This will return the original hash that was passed to meta().

Module: ember
index
Number
the current index of the iteration
previousObject
Object
the value returned by the last call to `nextObject`.
context
Object
a context object you can use to maintain state.
returns
Object
the next object in the iteration or undefined

Implement this method to make your class enumerable.

This method will be call repeatedly during enumeration. The index value will always begin with 0 and increment monotonically. You don't have to rely on the index value to determine what object to return, but you should always check the value and start from the beginning when you see the requested index is 0.

The previousObject is the object that was returned from the last call to nextObject for the current iteration. This is a useful way to manage iteration if you are tracing a linked list, for example.

Finally the context parameter will always contain a hash you can use as a "scratchpad" to maintain any other state you need in order to iterate properly. The context object is reused and is not reset between iterations so make sure you setup the context with a fresh state whenever the index parameter is 0.

Generally iterators will continue to call nextObject until the index reaches the your current length-1. If you run out of data before this time for some reason, you should simply return undefined.

The default implementation of this method simply looks up the index. This works great on any Array-like objects.

Module: ember
returns
Object
The removed object from the set or null.

Removes the last element from the set and returns it, or null if it's empty.

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var colors = new Ember.Set(["green", "blue"]);
colors.pop();  // "blue"
colors.pop();  // "green"
colors.pop();  // null
Module: ember
returns
Ember.Set
The set itself.

Inserts the given object on to the end of the set. It returns the set itself.

This is an alias for Ember.MutableEnumerable.addObject().

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var colors = new Ember.Set();
colors.push("red");   // ["red"]
colors.push("green"); // ["red", "green"]
colors.push("blue");  // ["red", "green", "blue"]
Module: ember
callback
Function
The callback to execute
initialValue
Object
Initial value for the reduce
reducerProperty
String
internal use only.
returns
Object
The reduced value.

This will combine the values of the enumerator into a single value. It is a useful way to collect a summary value from an enumeration. This corresponds to the reduce() method defined in JavaScript 1.8.

The callback method you provide should have the following signature (all parameters are optional):

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function(previousValue, item, index, enumerable);
  • previousValue is the value returned by the last call to the iterator.
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • enumerable is the enumerable object itself.

Return the new cumulative value.

In addition to the callback you can also pass an initialValue. An error will be raised if you do not pass an initial value and the enumerator is empty.

Note that unlike the other methods, this method does not allow you to pass a target object to set as this for the callback. It's part of the spec. Sorry.

Module: ember
callback
Function
The callback to execute
target
Object
The target object to use
returns
Array
A rejected array.

Returns an array with all of the items in the enumeration where the passed function returns false for. This method is the inverse of filter().

The callback method you provide should have the following signature (all parameters are optional):

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  function(item, index, enumerable);
  • item is the current item in the iteration.
  • index is the current index in the iteration
  • enumerable is the enumerable object itself.

It should return the a falsey value to include the item in the results.

Note that in addition to a callback, you can also pass an optional target object that will be set as "this" on the context. This is a good way to give your iterator function access to the current object.

Module: ember
key
String
the property to test
value
String
optional value to test against.
returns
Array
rejected array

Returns an array with the items that do not have truthy values for key. You can pass an optional second argument with the target value. Otherwise this will match any property that evaluates to false.

Module: ember
obj
Object
The object to remove
returns
Ember.Set
The set itself.

Removes the object from the set if it is found. If you pass a null value or an object that is already not in the set, this method will have no effect. This is an alias for Ember.MutableEnumerable.removeObject().

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var colors = new Ember.Set(["red", "green", "blue"]);
colors.remove("red");     // ["blue", "green"]
colors.remove("purple");  // ["blue", "green"]
colors.remove(null);      // ["blue", "green"]
Module: ember
objects
Ember.Enumerable
the objects to remove.
returns
Ember.Set
The set itself.

Removes each object in the passed enumerable to the set.

This is an alias of Ember.MutableEnumerable.removeObjects()

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var colors = new Ember.Set(["red", "green", "blue"]);
colors.removeEach(["red", "blue"]);  //  ["green"]
Module: ember
target
Object
opts
Hash
returns
this

Removes a registered enumerable observer.

Module: ember
object
Object
The object to remove from the enumerable.
returns
Object
the passed object

Required. You must implement this method to apply this mixin.

Attempts to remove the passed object from the receiver collection if the object is present in the collection. If the object is not present, this method has no effect.

If the passed object is of a type not supported by the receiver, then this method should raise an exception.

Module: ember
objects
Ember.Enumerable
the objects to remove
returns
Object
receiver

Removes each object in the passed enumerable from the receiver.

Module: ember

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

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

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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

Module: ember

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();

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

Module: ember
key
String
The key to set
value
Object
The object to set
returns
Object
receiver

Sets the value on the named property for each member. This is more efficient than using other methods defined on this helper. If the object implements Ember.Observable, the value will be changed to set(), otherwise it will be set directly. null objects are skipped.

Module: ember
returns
Object
The removed object from the set or null.

Removes the last element from the set and returns it, or null if it's empty.

This is an alias for Ember.Set.pop().

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var colors = new Ember.Set(["green", "blue"]);
colors.shift();  // "blue"
colors.shift();  // "green"
colors.shift();  // null
Module: ember
returns
Array
the enumerable as an array.

Simply converts the enumerable into a genuine array. The order is not guaranteed. Corresponds to the method implemented by Prototype.

Module: ember
returns
String
string representation

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>"
Module: ember
returns
Ember.Enumerable

Returns a new enumerable that contains only unique values. The default implementation returns an array regardless of the receiver type.

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var arr = ["a", "a", "b", "b"];
arr.uniq();  // ["a", "b"]
Module: ember
returns
Ember.Set
The set itself.

Inserts the given object on to the end of the set. It returns the set itself.

This is an alias of Ember.Set.push()

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var colors = new Ember.Set();
colors.unshift("red");    // ["red"]
colors.unshift("green");  // ["red", "green"]
colors.unshift("blue");   // ["red", "green", "blue"]
Module: ember

Override to implement teardown.

Module: ember
value
Object
returns
Ember.Enumerable

Returns a new enumerable that excludes the passed value. The default implementation returns an array regardless of the receiver type unless the receiver does not contain the value.

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var arr = ["a", "b", "a", "c"];
arr.without("a");  // ["b", "c"]