@polkadot/api/base/Events.js

Promise and RxJS wrappers around the Polkadot JS RPC

import { EventEmitter } from 'eventemitter3';
export class Events {
    __internal__eventemitter = new EventEmitter();
    emit(type, ...args) {
        return this.__internal__eventemitter.emit(type, ...args);
    }
    /**
     * @description Attach an eventemitter handler to listen to a specific event
     *
     * @param type The type of event to listen to. Available events are `connected`, `disconnected`, `ready` and `error`
     * @param handler The callback to be called when the event fires. Depending on the event type, it could fire with additional arguments.
     *
     * @example
     * <BR>
     *
     * ```javascript
     * api.on('connected', (): void => {
     *   console.log('API has been connected to the endpoint');
     * });
     *
     * api.on('disconnected', (): void => {
     *   console.log('API has been disconnected from the endpoint');
     * });
     * ```
     */
    on(type, handler) {
        this.__internal__eventemitter.on(type, handler);
        return this;
    }
    /**
     * @description Remove the given eventemitter handler
     *
     * @param type The type of event the callback was attached to. Available events are `connected`, `disconnected`, `ready` and `error`
     * @param handler The callback to unregister.
     *
     * @example
     * <BR>
     *
     * ```javascript
     * const handler = (): void => {
     *  console.log('Connected !);
     * };
     *
     * // Start listening
     * api.on('connected', handler);
     *
     * // Stop listening
     * api.off('connected', handler);
     * ```
     */
    off(type, handler) {
        this.__internal__eventemitter.removeListener(type, handler);
        return this;
    }
    /**
     * @description Attach an one-time eventemitter handler to listen to a specific event
     *
     * @param type The type of event to listen to. Available events are `connected`, `disconnected`, `ready` and `error`
     * @param handler The callback to be called when the event fires. Depending on the event type, it could fire with additional arguments.
     *
     * @example
     * <BR>
     *
     * ```javascript
     * api.once('connected', (): void => {
     *   console.log('API has been connected to the endpoint');
     * });
     *
     * api.once('disconnected', (): void => {
     *   console.log('API has been disconnected from the endpoint');
     * });
     * ```
     */
    once(type, handler) {
        this.__internal__eventemitter.once(type, handler);
        return this;
    }
}