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title ObservableArray
titleTemplate title - API / NativeScript
description Advanced array like class used when you want to be notified when a change occurs.
contributors false

Defined in: data/observable-array/index.ts

Advanced array like class used when you want to be notified when a change occurs.

Extends

Type Parameters

Type Parameter
T

Constructors

Constructor

new ObservableArray<T>(arrayLength?: number): ObservableArray<T>;

Defined in: data/observable-array/index.ts

Create ObservableArray<T> with specified length.

Parameters

Parameter Type
arrayLength? number

Returns

ObservableArray<T>

Overrides

Observable.constructor

Constructor

new ObservableArray<T>(items: T[]): ObservableArray<T>;

Defined in: data/observable-array/index.ts

Create ObservableArray<T> from source Array<T>.

Parameters

Parameter Type
items T[]

Returns

ObservableArray<T>

Overrides

Observable.constructor

Constructor

new ObservableArray<T>(...items: T[]): ObservableArray<T>;

Defined in: data/observable-array/index.ts

Create ObservableArray<T> from T items.

Parameters

Parameter Type
...items T[]

Returns

ObservableArray<T>

Overrides

Observable.constructor

Properties

changeEvent

static changeEvent: string;

Defined in: data/observable-array/index.ts

String value used when hooking to change event.

propertyChangeEvent

static propertyChangeEvent: string;

Defined in: data/observable/index.ts

String value used when hooking to propertyChange event.

Ns Event

propertyChange

Inherited from

Observable.propertyChangeEvent

Accessors

length

Get Signature

get length(): number;

Defined in: data/observable-array/index.ts

Gets or sets the length of the array. This is a number one higher than the highest element defined in an array.

Returns

number

Set Signature

set length(value: number): void;

Defined in: data/observable-array/index.ts

Parameters
Parameter Type
value number
Returns

void

Methods

_createPropertyChangeData()

_createPropertyChangeData(
   propertyName: string, 
   value: any, 
   oldValue?: any): PropertyChangeData;

Defined in: data/observable/index.ts

This method is intended to be overriden by inheritors to provide additional implementation.

Parameters

Parameter Type
propertyName string
value any
oldValue? any

Returns

PropertyChangeData

Inherited from

Observable._createPropertyChangeData

_emit()

_emit(eventName: string): void;

Defined in: data/observable/index.ts

Parameters

Parameter Type
eventName string

Returns

void

Inherited from

Observable._emit

_notifyLengthChange()

_notifyLengthChange(): void;

Defined in: data/observable-array/index.ts

Returns

void

[iterator]()

iterator: Generator<T, void, unknown>;

Defined in: data/observable-array/index.ts

Returns

Generator<T, void, unknown>

addEventListener()

addEventListener(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any, 
   once?: boolean): void;

Defined in: data/observable/index.ts

Adds a listener for the specified event name.

Parameters

Parameter Type Description
eventName string Name of the event to attach to.
callback (data: EventData) => void A function to be called when some of the specified event(s) is raised.
thisArg? any An optional parameter which when set will be used as "this" in callback method call.
once? boolean An optional parameter which when set will cause the event listener to fire once.

Returns

void

Inherited from

Observable.addEventListener

concat()

concat(...args: any[]): ObservableArray<T>;

Defined in: data/observable-array/index.ts

Combines two or more arrays.

Parameters

Parameter Type
...args any[]

Returns

ObservableArray<T>

every()

every(callbackfn: (value: T, index: number, array: ObservableArray<T>) => boolean, thisArg?: any): boolean;

Defined in: data/observable-array/index.ts

Determines whether all the members of an array satisfy the specified test.

Parameters

Parameter Type Description
callbackfn (value: T, index: number, array: ObservableArray<T>) => boolean A function that accepts up to three arguments. The every method calls the callbackfn function for each element in array1 until the callbackfn returns false, or until the end of the array.
thisArg? any An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.

Returns

boolean

filter()

filter(callbackfn: (value: T, index: number, array: ObservableArray<T>) => boolean, thisArg?: any): ObservableArray<T>;

Defined in: data/observable-array/index.ts

Returns the elements of an array that meet the condition specified in a callback function.

Parameters

Parameter Type Description
callbackfn (value: T, index: number, array: ObservableArray<T>) => boolean A function that accepts up to three arguments. The filter method calls the callbackfn function one time for each element in the array.
thisArg? any An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.

Returns

ObservableArray<T>

find()

find(callbackfn: (value: T, index: number, array: ObservableArray<T>) => any, thisArg?: any): T;

Defined in: data/observable-array/index.ts

Returns the first element in the array where predicate is true, and null otherwise.

Parameters

Parameter Type Description
callbackfn (value: T, index: number, array: ObservableArray<T>) => any -
thisArg? any If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.

Returns

T

findIndex()

findIndex(callbackfn: (value: T, index: number, array: ObservableArray<T>) => any, thisArg?: any): number;

Defined in: data/observable-array/index.ts

Returns the index of the first element in the array where predicate is true, and -1 otherwise.

Parameters

Parameter Type Description
callbackfn (value: T, index: number, array: ObservableArray<T>) => any -
thisArg? any If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.

Returns

number

forEach()

forEach(callbackfn: (value: T, index: number, array: ObservableArray<T>) => void, thisArg?: any): void;

Defined in: data/observable-array/index.ts

Performs the specified action for each element in an array.

Parameters

Parameter Type Description
callbackfn (value: T, index: number, array: ObservableArray<T>) => void A function that accepts up to three arguments. forEach calls the callbackfn function one time for each element in the array.
thisArg? any An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.

Returns

void

get()

get(name: string): any;

Defined in: data/observable/index.ts

Gets the value of the specified property.

Parameters

Parameter Type
name string

Returns

any

Inherited from

Observable.get

getItem()

getItem(pos: number): T;

Defined in: data/observable-array/index.ts

Returns item at specified position. Supports relative indexing from the end of the array when passed a negative index.

Parameters

Parameter Type
pos number

Returns

T

hasListeners()

hasListeners(eventName: string): boolean;

Defined in: data/observable/index.ts

Checks whether a listener is registered for the specified event name.

Parameters

Parameter Type Description
eventName string The name of the event to check for.

Returns

boolean

Inherited from

Observable.hasListeners

includes()

includes(searchElement: T, fromIndex?: number): boolean;

Defined in: data/observable-array/index.ts

Determines whether the specified element exists inside the array.

Parameters

Parameter Type Description
searchElement T The value to locate in the array.
fromIndex? number The array index at which to begin the search. If fromIndex is omitted, the search starts at index 0.

Returns

boolean

indexOf()

indexOf(searchElement: T, fromIndex?: number): number;

Defined in: data/observable-array/index.ts

Returns the index of the first occurrence of a value in an array.

Parameters

Parameter Type Description
searchElement T The value to locate in the array.
fromIndex? number The array index at which to begin the search. If fromIndex is omitted, the search starts at index 0.

Returns

number

join()

join(separator?: string): string;

Defined in: data/observable-array/index.ts

Adds all the elements of an array separated by the specified separator string.

Parameters

Parameter Type Description
separator? string A string used to separate one element of an array from the next in the resulting String. If omitted, the array elements are separated with a comma.

Returns

string

lastIndexOf()

lastIndexOf(searchElement: T, fromIndex?: number): number;

Defined in: data/observable-array/index.ts

Returns the index of the last occurrence of a specified value in an array.

Parameters

Parameter Type Description
searchElement T The value to locate in the array.
fromIndex? number The array index at which to begin the search. If fromIndex is omitted, the search starts at the last index in the array.

Returns

number

map()

map<U>(callbackfn: (value: T, index: number, array: ObservableArray<T>) => U, thisArg?: any): ObservableArray<U>;

Defined in: data/observable-array/index.ts

Calls a defined callback function on each element of an array, and returns an array that contains the results.

Type Parameters

Type Parameter
U

Parameters

Parameter Type Description
callbackfn (value: T, index: number, array: ObservableArray<T>) => U A function that accepts up to three arguments. The map method calls the callbackfn function one time for each element in the array.
thisArg? any An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.

Returns

ObservableArray<U>

notify()

notify<T>(data: T): void;

Defined in: data/observable/index.ts

Notify this Observable instance with some data. This causes all event handlers on the Observable instance to be called, as well as any 'global' event handlers set on the instance's class.

Type Parameters

Type Parameter
T extends Optional<EventData, "object">

Parameters

Parameter Type Description
data T an object that satisfies the EventData interface, though with an optional 'object' property. If left undefined, the 'object' property will implicitly be set as this Observable instance.

Returns

void

Inherited from

Observable.notify

notifyPropertyChange()

notifyPropertyChange(
   name: string, 
   value: any, 
   oldValue?: any): void;

Defined in: data/observable/index.ts

Notifies all the registered listeners for the property change event.

Parameters

Parameter Type
name string
value any
oldValue? any

Returns

void

Inherited from

Observable.notifyPropertyChange

off()

off(
   eventName: string, 
   callback?: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Removes the listener(s) for the specified event name.

Parameters

Parameter Type Description
eventName string The name of the event.
callback? (data: EventData) => void An optional specific event listener to remove (if omitted, all event listeners by this name will be removed).
thisArg? any An optional parameter which, when set, will be used to refine search of the correct event listener to be removed.

Returns

void

Inherited from

Observable.off

on()

Call Signature

on(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable-array/index.ts

Adds a listener for the specified event name.

Parameters
Parameter Type Description
eventName string The name of the event.
callback (data: EventData) => void The event listener to add. Will be called when an event of the given name is raised.
thisArg? any An optional parameter which, when set, will be bound as the this context when the callback is called. Falsy values will be not be bound.
Returns

void

Inherited from

Observable.on

Call Signature

on(
   event: "change", 
   callback: (args: ChangedData<T>) => void, 
   thisArg?: any): void;

Defined in: data/observable-array/index.ts

Parameters
Parameter Type
event "change"
callback (args: ChangedData<T>) => void
thisArg? any
Returns

void

Inherited from
Observable.on

once()

once(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Adds a listener for the specified event name, which, once fired, will remove itself.

Parameters

Parameter Type Description
eventName string The name of the event.
callback (data: EventData) => void The event listener to add. Will be called when an event of the given name is raised.
thisArg? any An optional parameter which, when set, will be bound as the this context when the callback is called. Falsy values will be not be bound.

Returns

void

Inherited from

Observable.once

pop()

pop(): T;

Defined in: data/observable-array/index.ts

Removes the last element from an array and returns it.

Returns

T

push()

push(...args: T[]): number;

Defined in: data/observable-array/index.ts

Appends new elements to an array, and returns the new length of the array.

Parameters

Parameter Type
...args T[]

Returns

number

reduce()

reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: ObservableArray<T>) => T, initialValue?: T): T;

Defined in: data/observable-array/index.ts

Calls the specified callback function for all the elements in an array. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.

Parameters

Parameter Type Description
callbackfn (previousValue: T, currentValue: T, currentIndex: number, array: ObservableArray<T>) => T A function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.
initialValue? T If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.

Returns

T

reduceRight()

reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: ObservableArray<T>) => T, initialValue?: T): T;

Defined in: data/observable-array/index.ts

Calls the specified callback function for all the elements in an array, in descending order. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.

Parameters

Parameter Type Description
callbackfn (previousValue: T, currentValue: T, currentIndex: number, array: ObservableArray<T>) => T A function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.
initialValue? T If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.

Returns

T

removeEventListener()

removeEventListener(
   eventName: string, 
   callback?: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Removes listener(s) for the specified event name.

Parameters

Parameter Type Description
eventName string Name of the event to attach to.
callback? (data: EventData) => void An optional parameter pointing to a specific listener. If not defined, all listeners for the event names will be removed.
thisArg? any An optional parameter which when set will be used to refine search of the correct callback which will be removed as event listener.

Returns

void

Inherited from

Observable.removeEventListener

reverse()

reverse(): ObservableArray<T>;

Defined in: data/observable-array/index.ts

Reverses the elements in an Array. This method uses 'in place' algorithm.

Returns

ObservableArray<T>

set()

set(name: string, value: any): void;

Defined in: data/observable/index.ts

Updates the specified property with the provided value.

Parameters

Parameter Type
name string
value any

Returns

void

Inherited from

Observable.set

setItem()

setItem(pos: number, value: T): void;

Defined in: data/observable-array/index.ts

Sets item at specified position. Supports relative indexing from the end of the array when passed a negative index.

Parameters

Parameter Type
pos number
value T

Returns

void

setProperty()

setProperty(name: string, value: any): void;

Defined in: data/observable/index.ts

Updates the specified property with the provided value and raises a property change event and a specific change event based on the property name.

Parameters

Parameter Type
name string
value any

Returns

void

Inherited from

Observable.setProperty

shift()

shift(): T;

Defined in: data/observable-array/index.ts

Removes the first element from an array and returns it.

Returns

T

slice()

slice(start?: number, end?: number): ObservableArray<T>;

Defined in: data/observable-array/index.ts

Returns a section of an array.

Parameters

Parameter Type Description
start? number The beginning of the specified portion of the array.
end? number The end of the specified portion of the array.

Returns

ObservableArray<T>

some()

some(callbackfn: (value: T, index: number, array: ObservableArray<T>) => boolean, thisArg?: any): boolean;

Defined in: data/observable-array/index.ts

Determines whether the specified callback function returns true for any element of an array.

Parameters

Parameter Type Description
callbackfn (value: T, index: number, array: ObservableArray<T>) => boolean A function that accepts up to three arguments. The some method calls the callbackfn function for each element in array1 until the callbackfn returns true, or until the end of the array.
thisArg? any An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.

Returns

boolean

sort()

sort(compareFn?: (a: T, b: T) => number): ObservableArray<T>;

Defined in: data/observable-array/index.ts

Sorts an array. This method uses 'in place' algorithm.

Parameters

Parameter Type Description
compareFn? (a: T, b: T) => number The name of the function used to determine the order of the elements. If omitted, the elements are sorted in ascending, ASCII character order.

Returns

ObservableArray<T>

splice()

splice(
   start: number, 
   deleteCount?: number, ...
items: T[]): ObservableArray<T>;

Defined in: data/observable-array/index.ts

Removes elements from an array and, if necessary, inserts new elements in their place, returning the deleted elements. This method uses 'in place' algorithm.

Parameters

Parameter Type Description
start number The zero-based location in the array from which to start removing elements.
deleteCount? number The number of elements to remove.
...items? T[] Elements to insert into the array in place of the deleted elements.

Returns

ObservableArray<T>

toJSON()

toJSON(): any[];

Defined in: data/observable-array/index.ts

Returns

any[]

toLocaleString()

toLocaleString(): string;

Defined in: data/observable-array/index.ts

Returns a date converted to a string using the current locale.

Returns

string

toString()

toString(): string;

Defined in: data/observable-array/index.ts

Returns a string representation of an array.

Returns

string

unshift()

unshift(...args: T[]): number;

Defined in: data/observable-array/index.ts

Inserts new elements at the start of an array.

Parameters

Parameter Type
...args T[]

Returns

number

addEventListener()

static addEventListener(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any, 
   once?: boolean): void;

Defined in: data/observable/index.ts

Please avoid using the static event-handling APIs as they will be removed in future.

Parameters

Parameter Type
eventName string
callback (data: EventData) => void
thisArg? any
once? boolean

Returns

void

Deprecated

Inherited from

Observable.addEventListener

off()

static off(
   eventName: string, 
   callback?: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Please avoid using the static event-handling APIs as they will be removed in future.

Parameters

Parameter Type
eventName string
callback? (data: EventData) => void
thisArg? any

Returns

void

Deprecated

Inherited from

Observable.off

on()

static on(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any, 
   once?: boolean): void;

Defined in: data/observable/index.ts

Please avoid using the static event-handling APIs as they will be removed in future.

Parameters

Parameter Type
eventName string
callback (data: EventData) => void
thisArg? any
once? boolean

Returns

void

Deprecated

Inherited from

Observable.on

once()

static once(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Please avoid using the static event-handling APIs as they will be removed in future.

Parameters

Parameter Type
eventName string
callback (data: EventData) => void
thisArg? any

Returns

void

Deprecated

Inherited from

Observable.once

removeEventListener()

static removeEventListener(
   eventName: string, 
   callback?: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Please avoid using the static event-handling APIs as they will be removed in future.

Parameters

Parameter Type
eventName string
callback? (data: EventData) => void
thisArg? any

Returns

void

Deprecated

Inherited from

Observable.removeEventListener