Class EmberArray

public
import EmberArray from '@ember/array';

This mixin implements Observer-friendly Array-like behavior. It is not a concrete implementation, but it can be used up by other classes that want to appear like arrays.

For example, ArrayProxy is a concrete classes that can be instantiated to implement array-like behavior. Both of these classes use the Array Mixin by way of the MutableArray mixin, which allows observable changes to be made to the underlying array.

This mixin defines methods specifically for collections that provide index-ordered access to their contents. When you are designing code that needs to accept any kind of Array-like object, you should use these methods instead of Array primitives because these will properly notify observers of changes to the array.

Although these methods are efficient, they do add a layer of indirection to your application so it is a good idea to use them only when you need the flexibility of using both true JavaScript arrays and "virtual" arrays such as controllers and collections.

You can use the methods defined in this module to access and modify array contents in a KVO-friendly way. You can also be notified whenever the membership of an array changes by using .observes('myArray.[]').

To support EmberArray in your own class, you must override two primitives to use it: length() and objectAt().

Show:

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

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 as 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.

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.

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

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

It must return a truthy value (i.e. true) to include an item in the results. Any non-truthy return value will discard the item from 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.

Usage Example:

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

If you are implementing an object that supports EmberArray, 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.

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
EmberArray
receiver

If you are implementing an object that supports EmberArray, 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.

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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let arr = ['a', null, 'c', undefined];
arr.compact();  // ['a', 'c']
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, array);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • array is the array 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();
}
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, array);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • array is the array itself.

It should return 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.

key
String
the property to test
value
*
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.

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 is similar to the find() method defined in ECMAScript 2015.

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

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function(item, index, array);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • array is the array 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.

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.

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

Iterates through the array, 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, array);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • array is the array 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.

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

Alias for mapBy

object
Object
The object to search for.
startAt
Number
optional starting location to search, default 0
returns
Boolean
`true` if object is found in the array.

Returns true if the passed object can be found in the array. This method is a Polyfill for ES 2016 Array.includes. If no startAt argument is given, the starting location to search is 0. If it's negative, searches from the index of this.length + startAt by asc.

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[1, 2, 3].includes(2);     // true
[1, 2, 3].includes(4);     // false
[1, 2, 3].includes(3, 2);  // true
[1, 2, 3].includes(3, 3);  // false
[1, 2, 3].includes(3, -1); // true
[1, 2, 3].includes(1, -1); // false
[1, 2, 3].includes(1, -4); // true
[1, 2, NaN].includes(NaN); // true
object
Object
the item to search for
startAt
Number
optional starting location to search, default 0
returns
Number
index or -1 if not found

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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let 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
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.

key
String
the property to test
value
String
optional value to test against. Defaults to `true`
returns
Boolean

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

key
String
the property to test
value
String
optional value to test against. Defaults to `true`
returns
Boolean

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

Note that like the native Array.every, isEvery will return true when called on any empty array.

object
Object
the item to search for
startAt
Number
optional starting location to search, default 0
returns
Number
index or -1 if not found

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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let 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
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, array);
  • item is the current item in the iteration.
  • index is the current index in the iteration.
  • array is the array 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.

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.

idx
Number
The index of the item to return.
returns
*
item at index or undefined

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 EmberArray. 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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let 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
indexes
Array
An array of indexes of items to return.
returns
Array

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

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let arr = ['a', 'b', 'c', 'd'];

arr.objectsAt([0, 1, 2]);  // ['a', 'b', 'c']
arr.objectsAt([2, 3, 4]);  // ['c', 'd', undefined]
callback
Function
The callback to execute
initialValue
Object
Initial value for the reduce
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, array);
  • 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.
  • array is the array 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.

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. 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, array);
  • item is the current item in the iteration.
  • index is the current index in the iteration
  • array is the array itself.

It should return 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.

key
String
the property to test
value
*
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.

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

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.

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 ergonomic than using other methods defined on this helper. If the object implements Observable, the value will be changed to set(), otherwise it will be set directly. null objects are skipped.

beginIndex
Number
(Optional) index to begin slicing from.
endIndex
Number
(Optional) index to end the slice at (but not included).
returns
Array
New array with specified slice

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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let arr = ['red', 'green', 'blue'];

arr.slice(0);       // ['red', 'green', 'blue']
arr.slice(0, 2);    // ['red', 'green']
arr.slice(1, 100);  // ['green', 'blue']
property
String
name(s) to sort on
returns
Array
The sorted array.

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

You may provide multiple arguments to sort by multiple properties.

returns
Array
the object as an array.

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

returns
EmberArray

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

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let arr = ['a', 'a', 'b', 'b'];
arr.uniq();  // ['a', 'b']

This only works on primitive data types, e.g. Strings, Numbers, etc.

key
String,Function
returns
EmberArray

Returns a new array that contains only items containing a unique property value. The default implementation returns an array regardless of the receiver type.

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let arr = [{ value: 'a' }, { value: 'a' }, { value: 'b' }, { value: 'b' }];
arr.uniqBy('value');  // [{ value: 'a' }, { value: 'b' }]

let arr = [2.2, 2.1, 3.2, 3.3];
arr.uniqBy(Math.floor);  // [2.2, 3.2];
value
Object
returns
EmberArray

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

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let arr = ['a', 'b', 'a', 'c'];
arr.without('a');  // ['b', 'c']