How to extend an Observable in JS using NS 8.4 ?

[rolandorocha]

Hi,

I had migrated Nativescript 6 Project to 8 and I'm getting this error: Class constructor Observable cannot be invoked without 'new'.

I use this View Model Base:

view-model-base.js

var __extends = (this && this.__extends) || function (d, b) {
        for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
        function __() { this.constructor = d; }
        __.prototype = b.prototype;
        d.prototype = new __();
    };
var observableModule = require("tns-core-modules/data/observable");
var dialogsModule = require("tns-core-modules/ui/dialogs");
var platformModule = require("tns-core-modules/platform");
var enumsModule = require("tns-core-modules/ui/enums");
var ViewModelBase = (function (_super) {
    __extends(ViewModelBase, _super);
    function ViewModelBase() {
        _super.call(this);
        this._loadingCount = 0;
    }
    Object.defineProperty(ViewModelBase.prototype, "isLoading", {
        get: function () {
            return this._isLoading;
        },
        set: function (value) {
            if (this._isLoading != value) {
                this._isLoading = value;
                this.notifyPropertyChanged("isLoading", value);
            }
        },
        enumerable: true,
        configurable: true
    });
    Object.defineProperty(ViewModelBase.prototype, "androidVisibility", {
        get: function () {
            if (platformModule.device.os === platformModule.platformNames.android) {
                return enumsModule.Visibility.visible;
            }
            return enumsModule.Visibility.collapsed;
        },
        enumerable: true,
        configurable: true
    });
    Object.defineProperty(ViewModelBase.prototype, "iosVisibility", {
        get: function () {
            if (platformModule.device.os === platformModule.platformNames.ios) {
                return enumsModule.Visibility.visible;
            }
            return enumsModule.Visibility.collapsed;
        },
        enumerable: true,
        configurable: true
    });
    ViewModelBase.prototype.beginLoading = function () {
        if (!this._loadingCount) {
            this.isLoading = true;
        }
        this._loadingCount++;
        return true;
    };
    ViewModelBase.prototype.endLoading = function () {
        if (this._loadingCount > 0) {
            this._loadingCount--;
            if (!this._loadingCount) {
                this.isLoading = false;
            }
        }
    };
    ViewModelBase.prototype.showError = function (error) {
        dialogsModule.alert({ title: global.lang("ERROR"), message: error, okButtonText: global.lang("CLOSE") });
    };
    ViewModelBase.prototype.showInfo = function (message) {
        dialogsModule.alert({ title: global.lang("INFO"), message: message, okButtonText: global.lang("OK") });
    };
    ViewModelBase.prototype.notifyPropertyChanged = function (propertyName, value) {
        this.notify({ object: this, eventName: observableModule.Observable.propertyChangeEvent, propertyName: propertyName, value: value });
    };
    return ViewModelBase;
})(observableModule.Observable);
exports.ViewModelBase = ViewModelBase;

I can't do this? Can you explain me how do I extend correctly the Observable class in my NS project?

I would thank you for any help.

Rolando

[farfromrefug]

@rolandorocha N 8 is using es6 classes. You cant mix up es5 and es6 classes. you need to use class ViewModelBase extends Observable {...}

[rolandorocha]

@farfromrefug I'm using JS, not TS. Because is not object-oriented programming, I think I'm not able to use your advice. If I used TS, I think I could configure tsconfig.json for accepting mix classes, but because I'm using JS I don´t know what I have to do for accept the Observable like a "extended" class.

[farfromrefug]

Classes is not a ts thing. You can use them in js too. That problem is not ts related