Ember.MutableArray Class packages/ember-runtime/lib/mixins/mutable_array.js:23


This mixin defines the API for modifying array-like objects. These methods can be applied only to a collection that keeps its items in an ordered set.

Note that an Array can change even if it does not implement this mixin. For example, one might implement a SparseArray that cannot be directly modified, but if its underlying enumerable changes, it will change also.

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addArrayObserver

(target, opts) Ember.Array

Adds an array observer to the receiving array. The array observer object normally must implement two methods:

  • arrayWillChange(observedObj, start, removeCount, addCount) - This method will be called just before the array is modified.
  • arrayDidChange(observedObj, start, removeCount, addCount) - This method will be called just after the array is modified.

Both callbacks will be passed the observed object, starting index of the change as well a a count of the items to be removed and added. You can use these callbacks to optionally inspect the array during the change, clear caches, or do any other bookkeeping necessary.

In addition to passing a target, you can also include an options hash which you can use to override the method names that will be invoked on the target.

Parameters:

target Object
The observer object.
opts Hash
Optional hash of configuration options including `willChange` and `didChange` option.

Returns:

Ember.Array
receiver

addEnumerableObserver

(target, opts)

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

Parameters:

target Object
opts Hash

Returns:

this

addObject

(object) 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.

Parameters:

object Object
The object to add to the enumerable.

Returns:

Object
the passed object

addObjects

(objects) Object

Adds each object in the passed enumerable to the receiver.

Parameters:

objects Ember.Enumerable
the objects to add.

Returns:

Object
receiver

any

(callback, target) Boolean

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(); }

Parameters:

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

anyBy

(key, value) Boolean

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.

Parameters:

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

arrayContentDidChange

(startIdx, removeAmt, addAmt) Ember.Array

If you are implementing an object that supports Ember.Array, call this method just after the array content changes to notify any observers and invalidate any related properties. Pass the starting index of the change as well as a delta of the amounts to change.

Parameters:

startIdx Number
The starting index in the array that did change.
removeAmt Number
The number of items that were removed. If you pass `null` assumes 0
addAmt Number
The number of items that were added. If you pass `null` assumes 0.

Returns:

Ember.Array
receiver

arrayContentWillChange

(startIdx, removeAmt, addAmt) Ember.Array

If you are implementing an object that supports Ember.Array, call this method just before the array content changes to notify any observers and invalidate any related properties. Pass the starting index of the change as well as a delta of the amounts to change.

Parameters:

startIdx Number
The starting index in the array that will change.
removeAmt Number
The number of items that will be removed. If you pass `null` assumes 0
addAmt Number
The number of items that will be added. If you pass `null` assumes 0.

Returns:

Ember.Array
receiver

clear

Ember.Array

Remove all elements from self. This is useful if you want to reuse an existing array without having to recreate it.

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var colors = ["red", "green", "blue"];
color.length();   //  3
colors.clear();   //  []
colors.length();  //  0

Returns:

Ember.Array
An empty Array.

compact

Array

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"]

Returns:

Array
the array without null and undefined elements.

contains

(obj) Boolean

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

Parameters:

obj Object
The object to search for.

Returns:

Boolean
`true` if object is found in enumerable.

enumerableContentDidChange

(start, removing, adding)

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.

Parameters:

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.

enumerableContentWillChange

(removing, adding)

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.

Parameters:

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.

every

(callback, target) 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(); }

Parameters:

callback Function
The callback to execute
target Object
The target object to use

Returns:

Boolean

everyBy

(key, value) 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.

Parameters:

key String
the property to test
value String
optional value to test against.

Returns:

Boolean

everyProperty

(key, value) Boolean deprecated

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.

Parameters:

key String
the property to test
value String
optional value to test against.

Returns:

Boolean

filter

(callback, target) 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.

Parameters:

callback Function
The callback to execute
target Object
The target object to use

Returns:

Array
A filtered array.

filterBy

(key, value) 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.

Parameters:

key String
the property to test
value String
optional value to test against.

Returns:

Array
filtered array

filterProperty

(key, value) Array deprecated

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.

Parameters:

key String
the property to test
value String
optional value to test against.

Returns:

Array
filtered array

find

(callback, target) Object

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.

Parameters:

callback Function
The callback to execute
target Object
The target object to use

Returns:

Object
Found item or `undefined`.

findBy

(key, value) Object

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.

Parameters:

key String
the property to test
value String
optional value to test against.

Returns:

Object
found item or `undefined`

findProperty

(key, value) Object deprecated

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.

Parameters:

key String
the property to test
value String
optional value to test against.

Returns:

Object
found item or `undefined`

forEach

(callback, target) Object

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.

Parameters:

callback Function
The callback to execute
target Object
The target object to use

Returns:

Object
receiver

getEach

(key) Array

Alias for mapBy

Parameters:

key String
name of the property

Returns:

Array
The mapped array.

indexOf

(object, startAt) Number

Returns the index of the given object's first occurrence. If no startAt argument is given, the starting location to search is 0. If it's negative, will count backward from the end of the array. Returns -1 if no match is found.

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var arr = ["a", "b", "c", "d", "a"];
arr.indexOf("a");       //  0
arr.indexOf("z");       // -1
arr.indexOf("a", 2);    //  4
arr.indexOf("a", -1);   //  4
arr.indexOf("b", 3);    // -1
arr.indexOf("a", 100);  // -1

Parameters:

object Object
the item to search for
startAt Number
optional starting location to search, default 0

Returns:

Number
index or -1 if not found

insertAt

(idx, object)

This will use the primitive replace() method to insert an object at the specified index.

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var colors = ["red", "green", "blue"];
colors.insertAt(2, "yellow");  // ["red", "green", "yellow", "blue"]
colors.insertAt(5, "orange");  // Error: Index out of range

Parameters:

idx Number
index of insert the object at.
object Object
object to insert

Returns:

this

invoke

(methodName, args) Array

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

Parameters:

methodName String
the name of the method
args Object...
optional arguments to pass as well.

Returns:

Array
return values from calling invoke.

lastIndexOf

(object, startAt) Number

Returns the index of the given object's last occurrence. If no startAt argument is given, the search starts from the last position. If it's negative, will count backward from the end of the array. Returns -1 if no match is found.

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var arr = ["a", "b", "c", "d", "a"];
arr.lastIndexOf("a");       //  4
arr.lastIndexOf("z");       // -1
arr.lastIndexOf("a", 2);    //  0
arr.lastIndexOf("a", -1);   //  4
arr.lastIndexOf("b", 3);    //  1
arr.lastIndexOf("a", 100);  //  4

Parameters:

object Object
the item to search for
startAt Number
optional starting location to search, default 0

Returns:

Number
index or -1 if not found

map

(callback, target) 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.

Parameters:

callback Function
The callback to execute
target Object
The target object to use

Returns:

Array
The mapped array.

mapBy

(key) Array

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

Parameters:

key String
name of the property

Returns:

Array
The mapped array.

mapProperty

(key) Array deprecated

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

Parameters:

key String
name of the property

Returns:

Array
The mapped array.

nextObject

(index, previousObject, context) Object

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.

Parameters:

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

objectAt

(idx) *

Returns the object at the given index. If the given index is negative or is greater or equal than the array length, returns undefined.

This is one of the primitives you must implement to support Ember.Array. If your object supports retrieving the value of an array item using get() (i.e. myArray.get(0)), then you do not need to implement this method yourself.

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var arr = ['a', 'b', 'c', 'd'];
arr.objectAt(0);   // "a"
arr.objectAt(3);   // "d"
arr.objectAt(-1);  // undefined
arr.objectAt(4);   // undefined
arr.objectAt(5);   // undefined

Parameters:

idx Number
The index of the item to return.

Returns:

*
item at index or undefined

objectsAt

(indexes) Array

This returns the objects at the specified indexes, using objectAt.

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var arr = ['a', 'b', 'c', 'd'];
arr.objectsAt([0, 1, 2]);  // ["a", "b", "c"]
arr.objectsAt([2, 3, 4]);  // ["c", "d", undefined]

Parameters:

indexes Array
An array of indexes of items to return.

Returns:

Array

popObject

Pop object from array or nil if none are left. Works just like pop() but it is KVO-compliant.

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var colors = ["red", "green", "blue"];
colors.popObject();   // "blue"
console.log(colors);  // ["red", "green"]

Returns:

object

pushObject

(obj) *

Push the object onto the end of the array. Works just like push() but it is KVO-compliant.

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var colors = ["red", "green", "blue"];
colors.pushObject("black");               // ["red", "green", "blue", "black"]
colors.pushObject(["yellow", "orange"]);  // ["red", "green", "blue", "black", ["yellow", "orange"]]

Parameters:

obj *
object to push

Returns:

*
the same obj passed as param

pushObjects

(objects) Ember.Array

Add the objects in the passed numerable to the end of the array. Defers notifying observers of the change until all objects are added.

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var colors = ["red", "green", "blue"];
colors.pushObjects(["black"]);               // ["red", "green", "blue", "black"]
colors.pushObjects(["yellow", "orange"]);  // ["red", "green", "blue", "black", "yellow", "orange"]

Parameters:

objects Ember.Enumerable
the objects to add

Returns:

Ember.Array
receiver

reduce

(callback, initialValue, reducerProperty) Object

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.

Parameters:

callback Function
The callback to execute
initialValue Object
Initial value for the reduce
reducerProperty String
internal use only.

Returns:

Object
The reduced value.

reject

(callback, target) 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.

Parameters:

callback Function
The callback to execute
target Object
The target object to use

Returns:

Array
A rejected array.

rejectBy

(key, value) 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.

Parameters:

key String
the property to test
value String
optional value to test against.

Returns:

Array
rejected array

rejectProperty

(key, value) Array deprecated

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.

Parameters:

key String
the property to test
value String
optional value to test against.

Returns:

Array
rejected array

removeArrayObserver

(target, opts) Ember.Array

Removes an array observer from the object if the observer is current registered. Calling this method multiple times with the same object will have no effect.

Parameters:

target Object
The object observing the array.
opts Hash
Optional hash of configuration options including `willChange` and `didChange` option.

Returns:

Ember.Array
receiver

removeAt

(start, len) Object

Remove an object at the specified index using the replace() primitive method. You can pass either a single index, or a start and a length.

If you pass a start and length that is beyond the length this method will throw an OUT_OF_RANGE_EXCEPTION

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var colors = ["red", "green", "blue", "yellow", "orange"];
colors.removeAt(0);     // ["green", "blue", "yellow", "orange"]
colors.removeAt(2, 2);  // ["green", "blue"]
colors.removeAt(4, 2);  // Error: Index out of range

Parameters:

start Number
index, start of range
len Number
length of passing range

Returns:

Object
receiver

removeEnumerableObserver

(target, opts)

Removes a registered enumerable observer.

Parameters:

target Object
opts Hash

Returns:

this

removeObject

(object) 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.

Parameters:

object Object
The object to remove from the enumerable.

Returns:

Object
the passed object

removeObjects

(objects) Object

Removes each object in the passed enumerable from the receiver.

Parameters:

objects Ember.Enumerable
the objects to remove

Returns:

Object
receiver

replace

(idx, amt, objects)

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

This is one of the primitives you must implement to support Ember.Array. You should replace amt objects started at idx with the objects in the passed array. You should also call this.enumerableContentDidChange()

Parameters:

idx Number
Starting index in the array to replace. If idx >= length, then append to the end of the array.
amt Number
Number of elements that should be removed from the array, starting at *idx*.
objects Array
An array of zero or more objects that should be inserted into the array at *idx*

reverseObjects

Ember.Array

Reverse objects in the array. Works just like reverse() but it is KVO-compliant.

Returns:

Ember.Array
receiver

setEach

(key, value) Object

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.

Parameters:

key String
The key to set
value Object
The object to set

Returns:

Object
receiver

setObjects

(objects) Ember.Array

Replace all the the receiver's content with content of the argument. If argument is an empty array receiver will be cleared.

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var colors = ["red", "green", "blue"];
colors.setObjects(["black", "white"]);  // ["black", "white"]
colors.setObjects([]);                  // []

Parameters:

objects Ember.Array
array whose content will be used for replacing the content of the receiver

Returns:

Ember.Array
receiver with the new content

shiftObject

Shift an object from start of array or nil if none are left. Works just like shift() but it is KVO-compliant.

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var colors = ["red", "green", "blue"];
colors.shiftObject();  // "red"
console.log(colors);   // ["green", "blue"]

Returns:

object

slice

(beginIndex, endIndex) Array

Returns a new array that is a slice of the receiver. This implementation uses the observable array methods to retrieve the objects for the new slice.

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var arr = ['red', 'green', 'blue'];
arr.slice(0);       // ['red', 'green', 'blue']
arr.slice(0, 2);    // ['red', 'green']
arr.slice(1, 100);  // ['green', 'blue']

Parameters:

beginIndex Integer
(Optional) index to begin slicing from.
endIndex Integer
(Optional) index to end the slice at.

Returns:

Array
New array with specified slice

some

(callback, target) Boolean deprecated

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.some(isManager)) { Paychecks.addBiggerBonus(); }

Parameters:

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

someProperty

(key, value) Boolean deprecated

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.

Parameters:

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

sortBy

(property) Array

Converts the enumerable into an array and sorts by the keys specified in the argument.

You may provide multiple arguments to sort by multiple properties.

Parameters:

property String
name(s) to sort on

Returns:

Array
The sorted array.

toArray

Array

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

Returns:

Array
the enumerable as an array.

uniq

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"]

Returns:

Ember.Enumerable

unshiftObject

(obj) *

Unshift an object to start of array. Works just like unshift() but it is KVO-compliant.

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var colors = ["red", "green", "blue"];
colors.unshiftObject("yellow");             // ["yellow", "red", "green", "blue"]
colors.unshiftObject(["black", "white"]);   // [["black", "white"], "yellow", "red", "green", "blue"]

Parameters:

obj *
object to unshift

Returns:

*
the same obj passed as param

unshiftObjects

(objects) Ember.Array

Adds the named objects to the beginning of the array. Defers notifying observers until all objects have been added.

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var colors = ["red", "green", "blue"];
colors.unshiftObjects(["black", "white"]);   // ["black", "white", "red", "green", "blue"]
colors.unshiftObjects("yellow");             // Type Error: 'undefined' is not a function

Parameters:

objects Ember.Enumerable
the objects to add

Returns:

Ember.Array
receiver

without

(value) 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"]

Parameters:

value Object

Returns:

Ember.Enumerable
Show:

@each

Returns a special object that can be used to observe individual properties on the array. Just get an equivalent property on this object and it will return an enumerable that maps automatically to the named key on the member objects.

If you merely want to watch for any items being added or removed to the array, use the [] property instead of @each.

Boolean

Becomes true whenever the array currently has observers watching changes on the array.

[]

This is the handler for the special array content property. If you get this property, it will return this. If you set this property it a new array, it will replace the current content.

This property overrides the default property defined in Ember.Enumerable.

Returns:

this

firstObject

Object

Helper method returns the first object from a collection. This is usually used by bindings and other parts of the framework to extract a single object if the enumerable contains only one item.

If you override this method, you should implement it so that it will always return the same value each time it is called. If your enumerable contains only one object, this method should always return that object. If your enumerable is empty, this method should return undefined.

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var arr = ["a", "b", "c"];
arr.get('firstObject');  // "a"

var arr = [];
arr.get('firstObject');  // undefined

Returns:

Object
the object or undefined

hasEnumerableObservers

Boolean

Becomes true whenever the array currently has observers watching changes on the array.

lastObject

Object

Helper method returns the last object from a collection. If your enumerable contains only one object, this method should always return that object. If your enumerable is empty, this method should return undefined.

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var arr = ["a", "b", "c"];
arr.get('lastObject');  // "c"

var arr = [];
arr.get('lastObject');  // undefined

Returns:

Object
the last object or undefined

length

Number

Your array must support the length property. Your replace methods should set this property whenever it changes.