varkeeper/src/index.js

let props = [];
let events = [];

Prop = function (name, value = undefined) {
    this._init(name, value);
}
Prop.prototype = {

    constructor: Prop,
    name: null,
    value: null,
    _init: function (name, value = undefined) {

        if ((value === undefined || value === null) && props.find(x => x.name === name) !== undefined) {
            myprop = props.find(x => x.name === name);
            setprop(name, myprop.value);
            this.value = myprop.value;
        }
        else {

            setprop(name, value);
            this.value = value;
        }


        this.name = name;

    },
    set: function (value) { setprop(this.name, value); },
    get: function () { return getprop(this.name); },
    delete: function () { deleteprop(this.name); },
    on: function (eventname, callback) { on(this.name, eventname, callback); }
}


function setprop(name, value) {

    if (value instanceof Function) {
        value = value();
    }


    var myprop = props.find(x => x.name === name)


    if (myprop != undefined) {
        on_function('set', name, value);
        if (value !== myprop.value) {
            myprop.value = value;
            on_function('change', name, value);
        }
    }
    else {
        props.push({ name: name, value: value });
        on_function('create', name, value);
    }


}

function getEventsFromTypeAndName(name, type) {
    let event = [];
    if (events.length > 0) {
        event = events.filter(x => x.name === name && x.type === type)
    }
    return event;
}

function getprop(name) {
    let result = props.find(x => x.name === name)
    if (result != undefined) {
        on_function('get', name, result.value);
        return result.value;
    }
    else {
        return undefined;
    }
}

function deleteprop(name) {
    props = props.filter(x => x.name !== name);
}

function on(eventname, name, callback) {
    events.push({ type: eventname, callback: callback, name: name });
}

function on_function(eventname, name, value) {
    let events = getEventsFromTypeAndName(name, eventname);
    if (events.length > 0) {
        switch (eventname) {
            case 'change':
            case 'create':
            case 'get':
            case 'set':
                events.forEach(x => x.callback(value));
                break;

            default:
                events.forEach(x => x.callback({ err: 404, msg: 'Event not found' }));
                break;
        }
    }
}


module.exports = { setprop, getprop, deleteprop, on, Prop }