ObservableArray - API / NativeScript

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

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

Extends

Observable

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

Extends ​

Type Parameters ​

Constructors ​

Constructor ​

Parameters ​

Returns ​

Overrides ​

Constructor ​

Parameters ​

Returns ​

Overrides ​

Constructor ​

Parameters ​

Returns ​

Overrides ​

Properties ​

changeEvent ​

propertyChangeEvent ​

Ns Event ​

Inherited from ​

Accessors ​

length ​

Get Signature ​

Returns ​

Set Signature ​

Parameters ​

Returns ​

Methods ​

_createPropertyChangeData() ​

Parameters ​

Returns ​

Inherited from ​

_emit() ​

Parameters ​

Returns ​

Inherited from ​

_notifyLengthChange() ​

Returns ​

[iterator]() ​

Returns ​

addEventListener() ​

Parameters ​

Returns ​

Inherited from ​

concat() ​

Parameters ​

Returns ​

every() ​

Parameters ​

Returns ​

filter() ​

Parameters ​

Returns ​

find() ​

Parameters ​

Returns ​

findIndex() ​

Parameters ​

Returns ​

forEach() ​

Parameters ​

Returns ​

get() ​

Parameters ​

Returns ​

Inherited from ​

getItem() ​

Parameters ​

Returns ​

hasListeners() ​

Parameters ​

Returns ​

Inherited from ​

includes() ​

Parameters ​

Returns ​

indexOf() ​

Parameters ​

Returns ​

join() ​

Extends

Type Parameters

Constructors

Constructor

Parameters

Returns

Overrides

Constructor

Parameters

Returns

Overrides

Constructor

Parameters

Returns

Overrides

Properties

changeEvent

propertyChangeEvent

Ns Event

Inherited from

Accessors

length

Get Signature

Returns

Set Signature

Parameters

Returns

Methods

_createPropertyChangeData()

Parameters

Returns

Inherited from

_emit()

Parameters

Returns

Inherited from

_notifyLengthChange()

Returns

[iterator]()

Returns

addEventListener()

Parameters

Returns

Inherited from

concat()

Parameters

Returns

every()

Parameters

Returns

filter()

Parameters

Returns

find()

Parameters

Returns

findIndex()

Parameters

Returns

forEach()

Parameters

Returns

get()

Parameters

Returns

Inherited from

getItem()

Parameters

Returns

hasListeners()

Parameters

Returns

Inherited from

includes()

Parameters

Returns

indexOf()

Parameters

Returns

join()