vasille/lib/models/listener.js

The same framework which is designed to build bulletproof frontends (core library).

/**
 * Represent a listener for a model
 * @class Listener
 */
export class Listener {
    /**
     * Functions to run on adding new items
     * @type Set
     */
    onAdded = new Set();
    /**
     * Functions to run on item removing
     * @type Set
     */
    onRemoved = new Set();
    /**
     * Emits added event to listeners
     * @param index {*} index of value
     * @param value {*} value of added item
     */
    emitAdded(index, value) {
        this.onAdded.forEach(handler => {
            handler(index, value);
        });
    }
    /**
     * Emits removed event to listeners
     * @param index {*} index of removed value
     * @param value {*} value of removed item
     */
    emitRemoved(index, value) {
        this.onRemoved.forEach(handler => {
            handler(index, value);
        });
    }
    /**
     * Adds a handler to added event
     * @param handler {function} function to run on event emitting
     */
    onAdd(handler) {
        this.onAdded.add(handler);
    }
    /**
     * Adds a handler to removed event
     * @param handler {function} function to run on event emitting
     */
    onRemove(handler) {
        this.onRemoved.add(handler);
    }
    /**
     * Removes a handler from added event
     * @param handler {function} handler to remove
     */
    offAdd(handler) {
        this.onAdded.delete(handler);
    }
    /**
     * Removes a handler form removed event
     * @param handler {function} handler to remove
     */
    offRemove(handler) {
        this.onRemoved.delete(handler);
    }
}