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Observable | API - NativeScript

Observable is used when you want to be notified when a change occurs. Use on/off methods to add/remove listener. Please note that should you be using the `new Observable({})` constructor, it is **obsolete** since v3.0, and you have to migrate to the "data/observable" `fromObject({})` or the `fromObjectRecursive({})` functions.

Summary ​

Constructors ​

constructor ​

Properties ​

propertyChangeEvent ​

Static

propertyChangeEvent: string

String value used when hooking to propertyChange event.

Methods ​

_createPropertyChangeData ​

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

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

_emit ​

_emit(eventNames: string): void

addEventListener ​

addEventListener(eventNames: string, callback: (data: EventData) => void, thisArg?: any): void

Adds a listener for the specified event name.

get ​

Gets the value of the specified property.

hasListeners ​

hasListeners(eventName: string): boolean

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

notify ​

notify<T>(data: T): void

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.

notifyPropertyChange ​

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

Notifies all the registered listeners for the property change event.

off ​

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

Shortcut alias to the removeEventListener method.

on ​

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

A basic method signature to hook an event listener (shortcut alias to the addEventListener method).

once ​

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

Adds one-time listener function for the event named `event`.

removeEventListener ​

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

Removes listener(s) for the specified event name.

set ​

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

Updates the specified property with the provided value.

setProperty ​

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

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

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

removeEventListener ​

Static

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

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