Class EmberArray

public
Uses: Enumerable
Since: vEmber 0.9.0
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 class that can be instantiated to implement array-like behavior. This class uses 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 an observable-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:

Module: @ember/array
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

The any() method executes the callback function once for each element present in the array until it finds the one where callback returns a truthy value (i.e. true). If such an element is found, any() immediately returns true. Otherwise, any() returns false.

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.

Note that in addition to a callback, you can also pass an optional target object that will be set as this on the context. It can be a good way to give your iterator function access to an object in cases where an ES6 arrow function would not be appropriate.

Usage Example:

let includesManager = people.any(this.findPersonInManagersList, this);

let includesStockHolder = people.any(person => {
  return this.findPersonInStockHoldersList(person)
});

if (includesManager || includesStockHolder) {
  Paychecks.addBiggerBonus();
}
Module: @ember/array
returns
Array

the array without null and undefined elements.

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

let arr = ['a', null, 'c', undefined];
arr.compact();  // ['a', 'c']
Module: @ember/array
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 Array.prototype.every() method defined in ES5.

The callback method should have the following signature:

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.

All params are optional. The method should return 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.

Usage example:

function isAdult(person) {
  return person.age > 18;
};

const people = Ember.A([{ name: 'John', age: 24 }, { name: 'Joan', age: 45 }]);
const areAllAdults = people.every(isAdult);
Module: @ember/array
callback
Function

The callback to execute

target
Object

The target object to use

returns
Array

A filtered array.

Returns a new array with all of the items in the enumeration that the provided callback function returns true for. This method corresponds to Array.prototype.filter().

The callback method should have the following signature:

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.

All parameters are optional. The function should return true to include the item in the results, and false otherwise.

Example:

function isAdult(person) {
  return person.age > 18;
};

let people = Ember.A([{ name: 'John', age: 14 }, { name: 'Joan', age: 45 }]);

people.filter(isAdult); // returns [{ name: 'Joan', age: 45 }];

Note that in addition to a callback, you can 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. For example:

function isAdultAndEngineer(person) {
  return person.age > 18 && this.engineering;
}

class AdultsCollection {
  engineering = false;

  constructor(opts = {}) {
    super(...arguments);

    this.engineering = opts.engineering;
    this.people = Ember.A([{ name: 'John', age: 14 }, { name: 'Joan', age: 45 }]);
  }
}

let collection = new AdultsCollection({ engineering: true });
collection.people.filter(isAdultAndEngineer, { target: collection });
Module: @ember/array
key
String

the property to test

value
*

optional value to test against.

returns
Array

filtered array

Filters the array by the property and an optional value. If a value is given, it returns the items that have said value for the property. If not, it returns all the items that have a truthy value for the property.

Example Usage:

let things = Ember.A([{ food: 'apple', isFruit: true }, { food: 'beans', isFruit: false }]);

things.filterBy('food', 'beans'); // [{ food: 'beans', isFruit: false }]
things.filterBy('isFruit'); // [{ food: 'apple', isFruit: true }]
Module: @ember/array
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):

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.

Example Usage:

let users = [
  { id: 1, name: 'Yehuda' },
  { id: 2, name: 'Tom' },
  { id: 3, name: 'Melanie' },
  { id: 4, name: 'Leah' }
];

users.find((user) => user.name == 'Tom'); // [{ id: 2, name: 'Tom' }]
users.find(({ id }) => id == 3); // [{ id: 3, name: 'Melanie' }]
Module: @ember/array
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.

Usage Example:

let users = [
  { id: 1, name: 'Yehuda', isTom: false },
  { id: 2, name: 'Tom', isTom: true },
  { id: 3, name: 'Melanie', isTom: false },
  { id: 4, name: 'Leah', isTom: false }
];

users.findBy('id', 4); // { id: 4, name: 'Leah', isTom: false }
users.findBy('name', 'Melanie'); // { id: 3, name: 'Melanie', isTom: false }
users.findBy('isTom'); // { id: 2, name: 'Tom', isTom: true }
Module: @ember/array
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):

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.

Example Usage:

let foods = [
  { name: 'apple', eaten: false },
  { name: 'banana', eaten: false },
  { name: 'carrot', eaten: false }
];

foods.forEach((food) => food.eaten = true);

let output = '';
foods.forEach((item, index, array) =>
  output += `${index + 1}/${array.length} ${item.name}\n`;
);
console.log(output);
// 1/3 apple
// 2/3 banana
// 3/3 carrot
Module: @ember/array
key
String

name of the property

returns
Array

The mapped array.

Alias for mapBy.

Returns the value of the named property on all items in the enumeration.

let people = [{name: 'Joe'}, {name: 'Matt'}];

people.getEach('name');
// ['Joe', 'Matt'];

people.getEach('nonexistentProperty');
// [undefined, undefined];
Module: @ember/array
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.

Used to determine if the array contains the passed object. Returns true if found, false otherwise.

The optional startAt argument can be used to pass a starting index to search from, effectively slicing the searchable portion of the array. If it's negative it will add the array length to the startAt value passed in as the index to search from. If less than or equal to -1 * array.length the entire array is searched.

This method has the same behavior of JavaScript's Array.includes.

[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
Module: @ember/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

Used to determine the passed object's first occurrence in the array. Returns the index if found, -1 if no match is found.

The optional startAt argument can be used to pass a starting index to search from, effectively slicing the searchable portion of the array. If it's negative it will add the array length to the startAt value passed in as the index to search from. If less than or equal to -1 * array.length the entire array is searched.

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, equivalent to indexOf('a', 4)
arr.indexOf('a', -100); //  0, searches entire array
arr.indexOf('b', 3);    // -1
arr.indexOf('a', 100);  // -1

let people = [{ name: 'Zoey' }, { name: 'Bob' }]
let newPerson = { name: 'Tom' };
people = [newPerson, ...people, newPerson];

people.indexOf(newPerson);     //  0
people.indexOf(newPerson, 1);  //  3
people.indexOf(newPerson, -4); //  0
people.indexOf(newPerson, 10); // -1
Module: @ember/array
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.

class Person {
  name = null;

  constructor(name) {
    this.name = name;
  }

  greet(prefix='Hello') {
    return `${prefix} ${this.name}`;
  }
}

let people = [new Person('Joe'), new Person('Matt')];

people.invoke('greet'); // ['Hello Joe', 'Hello Matt']
people.invoke('greet', 'Bonjour'); // ['Bonjour Joe', 'Bonjour Matt']
Module: @ember/array

Available since v1.3.0

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.

Example usage:

const food = [
  { food: 'apple', isFruit: true },
  { food: 'bread', isFruit: false },
  { food: 'banana', isFruit: true }
];

food.isAny('isFruit'); // true
Module: @ember/array

Available since v1.3.0

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.

class Language {
  constructor(name, isProgrammingLanguage) {
    this.name = name;
    this.programmingLanguage = isProgrammingLanguage;
  }
}

const compiledLanguages = [
  new Language('Java', true),
  new Language('Go', true),
  new Language('Rust', true)
]

const languagesKnownByMe = [
  new Language('Javascript', true),
  new Language('English', false),
  new Language('Ruby', true)
]

compiledLanguages.isEvery('programmingLanguage'); // true
languagesKnownByMe.isEvery('programmingLanguage'); // false
Module: @ember/array
object
Object

the item to search for

startAt
Number

optional starting location to search from backwards, defaults to (array.length - 1)

returns
Number

The last index of the object in the array 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 greater than or equal to the length of the array, the search starts from the last position.
  • If it's negative, it is taken as the offset from the end of the array i.e. startAt + array.length.
  • If it's any other positive number, will search backwards from that index of the array.

Returns -1 if no match is found.

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('a', -3);   //  0
arr.lastIndexOf('b', 3);    //  1
arr.lastIndexOf('a', 100);  //  4
Module: @ember/array
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):

function(item, index, array);
let arr = [1, 2, 3, 4, 5, 6];

arr.map(element => element * element);
// [1, 4, 9, 16, 25, 36];

arr.map((element, index) => element + index);
// [1, 3, 5, 7, 9, 11];
  • 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.

Module: @ember/array
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.

let people = [{name: 'Joe'}, {name: 'Matt'}];

people.mapBy('name');
// ['Joe', 'Matt'];

people.mapBy('unknownProperty');
// [undefined, undefined];
Module: @ember/array
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.

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
Module: @ember/array
indexes
Array

An array of indexes of items to return.

returns
Array

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

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

arr.objectsAt([0, 1, 2]);  // ['a', 'b', 'c']
arr.objectsAt([2, 3, 4]);  // ['c', 'd', undefined]
Module: @ember/array
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 array into a single value. It is a useful way to collect a summary value from an array. 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, 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.

Example Usage:

  let numbers = [1, 2, 3, 4, 5];

  numbers.reduce(function(summation, current) {
    return summation + current;
  }); // 15 (1 + 2 + 3 + 4 + 5)

  numbers.reduce(function(summation, current) {
    return summation + current;
  }, -15); // 0 (-15 + 1 + 2 + 3 + 4 + 5)


  let binaryValues = [true, false, false];

  binaryValues.reduce(function(truthValue, current) {
    return truthValue && current;
  }); // false (true && false && false)
Module: @ember/array
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):

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.

Example Usage:

const food = [
  { food: 'apple', isFruit: true },
  { food: 'bread', isFruit: false },
  { food: 'banana', isFruit: true }
];
const nonFruits = food.reject(function(thing) {
  return thing.isFruit;
}); // [{food: 'bread', isFruit: false}]
Module: @ember/array
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 the provided key. You can pass an optional second argument with a target value to reject for the key. Otherwise this will reject objects where the provided property evaluates to false.

Example Usage:

  let food = [
    { name: "apple", isFruit: true },
    { name: "carrot", isFruit: false },
    { name: "bread", isFruit: false },
  ];
  food.rejectBy('isFruit'); // [{ name: "carrot", isFruit: false }, { name: "bread", isFruit: false }]
  food.rejectBy('name', 'carrot'); // [{ name: "apple", isFruit: true }}, { name: "bread", isFruit: false }]
Module: @ember/array
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.

let people = [{name: 'Joe'}, {name: 'Matt'}];

people.setEach('zipCode', '10011');
// [{name: 'Joe', zipCode: '10011'}, {name: 'Matt', zipCode: '10011'}];
Module: @ember/array
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.

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

arr.slice(0);       // ['red', 'green', 'blue']
arr.slice(0, 2);    // ['red', 'green']
arr.slice(1, 100);  // ['green', 'blue']
Module: @ember/array

Available since v1.2.0

property
String

name(s) to sort on

returns
Array

The sorted array.

Sorts the array by the keys specified in the argument.

You may provide multiple arguments to sort by multiple properties.

   let colors = [
 { name: 'red', weight: 500 },
 { name: 'green', weight: 600 },
 { name: 'blue', weight: 500 }
];

   colors.sortBy('name');
   // [{name: 'blue', weight: 500}, {name: 'green', weight: 600}, {name: 'red', weight: 500}]

   colors.sortBy('weight', 'name');
   // [{name: 'blue', weight: 500}, {name: 'red', weight: 500}, {name: 'green', weight: 600}]
Module: @ember/array
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.

Module: @ember/array
returns
EmberArray

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

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

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

Module: @ember/array
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.

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];
Module: @ember/array
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.

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