Ember.Enumerable Class
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:
-
You must have a length property. This property should change whenever the number of items in your enumerable object changes. If you use this with an
Ember.Object
subclass, you should be sure to change the length property usingset().
-
You must implement
nextObject().
See documentation.
Once you have these two methods implemented, 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.
Item Index
Methods
- addEnumerableObserver
- any
- anyBy deprecated
- compact
- contains
- enumerableContentDidChange
- enumerableContentWillChange
- every
- everyBy deprecated
- everyProperty deprecated
- filter
- filterBy
- filterProperty deprecated
- find
- findBy
- findProperty deprecated
- forEach
- getEach
- invoke
- isAny
- isEvery
- map
- mapBy
- mapProperty deprecated
- nextObject
- reduce
- reject
- rejectBy
- rejectProperty deprecated
- removeEnumerableObserver
- setEach
- some deprecated
- someProperty deprecated
- sortBy
- toArray
- uniq
- without
Properties
Methods
addEnumerableObserver
-
target
-
[opts]
Registers an enumerable observer. Must implement Ember.EnumerableObserver
mixin.
Parameters:
-
target
Object -
[opts]
Hash optional
Returns:
this
any
-
callback
-
[target]
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):
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:
if (people.any(isManager)) { Paychecks.addBiggerBonus(); }
Parameters:
-
callback
FunctionThe callback to execute
-
[target]
Object optionalThe target object to use
Returns:
true
if the passed function returns true
for any item
anyBy
-
key
-
[value]
Returns:
true
if the passed function returns true
for any item
compact
()
Array
Returns a copy of the array with all null and undefined elements removed.
var arr = ["a", null, "c", undefined];
arr.compact(); // ["a", "c"]
Returns:
the array without null and undefined elements.
contains
-
obj
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.
var arr = ["a", "b", "c"];
arr.contains("a"); // true
arr.contains("z"); // false
Parameters:
-
obj
ObjectThe object to search for.
Returns:
true
if object is found in enumerable.
enumerableContentDidChange
-
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:
-
removing
Ember.Enumerable | NumberAn enumerable of the objects to be removed or the number of items to be removed.
-
adding
Ember.Enumerable | NumberAn 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 | NumberAn enumerable of the objects to be removed or the number of items to be removed.
-
adding
Ember.Enumerable | NumberAn enumerable of the objects to be added or the number of items to be added.
every
-
callback
-
[target]
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):
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:
if (people.every(isEngineer)) { Paychecks.addBigBonus(); }
Parameters:
-
callback
FunctionThe callback to execute
-
[target]
Object optionalThe target object to use
Returns:
everyBy
-
key
-
[value]
Returns:
everyProperty
-
key
-
[value]
Returns:
filter
-
callback
-
[target]
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):
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
FunctionThe callback to execute
-
[target]
Object optionalThe target object to use
Returns:
A filtered array.
filterBy
-
key
-
[value]
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
Stringthe property to test
-
[value]
optionaloptional value to test against.
Returns:
filtered array
filterProperty
-
key
-
[value]
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
.
Returns:
filtered array
find
-
callback
-
[target]
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):
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
FunctionThe callback to execute
-
[target]
Object optionalThe target object to use
Returns:
Found item or undefined
.
findBy
-
key
-
[value]
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.
Returns:
found item or undefined
findProperty
-
key
-
[value]
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.
Returns:
found item or undefined
forEach
-
callback
-
[target]
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):
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
FunctionThe callback to execute
-
[target]
Object optionalThe target object to use
Returns:
receiver
getEach
-
key
Alias for mapBy
Parameters:
-
key
Stringname of the property
Returns:
The mapped array.
invoke
-
methodName
-
args
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
Stringthe name of the method
-
args
Object...optional arguments to pass as well.
Returns:
return values from calling invoke.
isAny
-
key
-
[value]
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.
Returns:
true
if the passed function returns true
for any item
isEvery
-
key
-
[value]
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.
Returns:
map
-
callback
-
[target]
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):
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
FunctionThe callback to execute
-
[target]
Object optionalThe target object to use
Returns:
The mapped array.
mapBy
-
key
Similar to map, this specialized function returns the value of the named property on all items in the enumeration.
Parameters:
-
key
Stringname of the property
Returns:
The mapped array.
mapProperty
-
key
Similar to map, this specialized function returns the value of the named property on all items in the enumeration.
Parameters:
-
key
Stringname of the property
Returns:
The mapped array.
nextObject
-
index
-
previousObject
-
context
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
Numberthe current index of the iteration
-
previousObject
Objectthe value returned by the last call to
nextObject
. -
context
Objecta context object you can use to maintain state.
Returns:
the next object in the iteration or undefined
reduce
-
callback
-
initialValue
-
reducerProperty
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):
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:
Returns:
The reduced value.
reject
-
callback
-
[target]
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):
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
FunctionThe callback to execute
-
[target]
Object optionalThe target object to use
Returns:
A rejected array.
rejectBy
-
key
-
[value]
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.
Returns:
rejected array
rejectProperty
-
key
-
[value]
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.
Returns:
rejected array
removeEnumerableObserver
-
target
-
[opts]
Removes a registered enumerable observer.
Parameters:
-
target
Object -
[opts]
Hash optional
Returns:
this
setEach
-
key
-
value
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
StringThe key to set
-
value
ObjectThe object to set
Returns:
receiver
some
-
callback
-
[target]
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):
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:
if (people.some(isManager)) { Paychecks.addBiggerBonus(); }
Parameters:
-
callback
FunctionThe callback to execute
-
[target]
Object optionalThe target object to use
Returns:
true
if the passed function returns true
for any item
someProperty
-
key
-
[value]
Returns:
true
if the passed function returns true
for any item
sortBy
-
property
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
Stringname(s) to sort on
Returns:
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:
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.
var arr = ["a", "a", "b", "b"];
arr.uniq(); // ["a", "b"]
Returns:
without
-
value
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.
var arr = ["a", "b", "a", "c"];
arr.without("a"); // ["b", "c"]
Parameters:
-
value
Object
Returns:
Properties
[]
Array
This property will trigger anytime the enumerable's content changes. You can observe this property to be notified of changes to the enumerables content.
For plain enumerables, this property is read only. Array
overrides
this method.
firstObject
Unknown
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
.
var arr = ["a", "b", "c"];
arr.get('firstObject'); // "a"
var arr = [];
arr.get('firstObject'); // undefined
hasEnumerableObservers
Boolean
Becomes true whenever the array currently has observers watching changes on the array.
lastObject
Unknown
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
.
var arr = ["a", "b", "c"];
arr.get('lastObject'); // "c"
var arr = [];
arr.get('lastObject'); // undefined