vasille/lib/value/reference.js

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

import { IValue } from "../core/ivalue.js";
import { reportError } from "../functional/safety.js";
/**
 * Declares a notifiable value
 * @class Reference
 * @extends IValue
 */
export class Reference extends IValue {
    /**
     * The encapsulated value
     * @type {*}
     */
    state;
    /**
     * Array of handlers
     * @type {Set}
     * @readonly
     */
    onChange;
    /**
     * @param value {any} the initial value
     */
    constructor(value) {
        super();
        this.state = value;
        this.onChange = new Set();
    }
    get V() {
        return this.state;
    }
    set V(value) {
        if (this.state !== value) {
            this.state = value;
            this.onChange.forEach(handler => {
                try {
                    handler(value);
                }
                catch (e) {
                    reportError(e);
                }
            });
        }
    }
    on(handler) {
        this.onChange.add(handler);
    }
    off(handler) {
        this.onChange.delete(handler);
    }
}