Class Ember.Enumerable

Defined in: packages/ember-runtime/lib/mixins/enumerable.js:35
Module: ember
Since: vEmber 0.9

This mixin defines the common interface implemented by enumerable objects in Ember. Most of these methods follow the standard Array iteration API defined up to JavaScript 1.8 (excluding language-specific features that cannot be emulated in older versions of JavaScript).

This mixin is applied automatically to the Array class on page load, so you can use any of these methods on simple arrays. If Array already implements one of these methods, the mixin will not override them.

Writing Your Own Enumerable

To make your own custom class enumerable, you need two items:

  1. You must have a length property. This property should change whenever the number of items in your enumerable object changes. If you using this with an Ember.Object subclass, you should be sure to change the length property using set().

  2. If you must implement nextObject(). See documentation.

Once you have these two methods implement, apply the Ember.Enumerable mixin to your class and you will be able to enumerate the contents of your object like any other collection.

Using Ember Enumeration with Other Libraries

Many other libraries provide some kind of iterator or enumeration like facility. This is often where the most common API conflicts occur. Ember's API is designed to be as friendly as possible with other libraries by implementing only methods that mostly correspond to the JavaScript 1.8 API.

Show:

addEnumerableObserver (target, opts)

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:838

target
Object
opts
Hash
returns
this

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

any (callback, target) Boolean

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:578

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):

1

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:

1

if (people.any(isManager)) { Paychecks.addBiggerBonus(); }

anyBy (key, value) Boolean

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:653

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.

compact Array

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:760

returns
Array
the array without null and undefined elements.

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

1
2

var arr = ["a", null, "c", undefined];
arr.compact();  // ["a", "c"]

contains (obj) Boolean

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:168

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.

1
2
3

var arr = ["a", "b", "c"];
arr.contains("a"); // true
arr.contains("z"); // false

enumerableContentDidChange (start, removing, adding)

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:927

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.

enumerableContentWillChange (removing, adding)

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:891

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.

every (callback, target) Boolean

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:515

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):

1

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:

1

if (people.every(isEngineer)) { Paychecks.addBigBonus(); }

everyBy (key, value) Boolean

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:553

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.

filter (callback, target) Array

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:316

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):

1

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.

filterBy (key, value) Array

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:382

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.

find (callback, target) Object

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:440

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):

1

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.

findBy (key, value) Object

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:484

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.

forEach (callback, target) Object

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:187

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):

1

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.

getEach (key) Array

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:228

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

Alias for mapBy

invoke (methodName, args) Array

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:723

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.

map (callback, target) Array

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:256

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):

1

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.

mapBy (key) Array

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:290

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.

nextObject (index, previousObject, context) Object

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:74

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.

reduce (callback, initialValue, reducerProperty) Object

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:678

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):

1

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.

reject (callback, target) Array

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:352

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):

1

  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.

rejectBy (key, value) Array

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:409

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.

removeEnumerableObserver (target, opts)

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:859

target
Object
opts
Hash
returns
this

Removes a registered enumerable observer.

setEach (key, value) Object

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:239

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.

toArray Array

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:747

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.

uniq Ember.Enumerable

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:798

returns
Ember.Enumerable

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

1
2

var arr = ["a", "a", "b", "b"];
arr.uniq();  // ["a", "b"]

without (value) Ember.Enumerable

Module: ember

Defined in packages/ember-runtime/lib/mixins/enumerable.js:775

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.

1
2

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