Nativescript-cli: Android build fails when using 'isAndroid' from nativescript/core within main.ts (app.ts)

[felixkrautschuk]

Environment
Provide version numbers for the following components (information can be retrieved by running tns info in your project folder or by inspecting the package.json of the project):

• CLI: 7.0.10
• Cross-platform modules: 7.0.11
• Android Runtime: 7.0.0
• iOS Runtime: 7.0.0
• XCode Version: 11.7
• Plugin(s): -

Describe the bug
I am not sure if this issue is related to the nativescript-cli or maybe more to webpack, but let my try to explain it here first.

When importing _isAndroid_ from "@nativescript/core" within the main.ts (app.ts) file, the app will not build on Android. On iOS, everything works as expected.

ERROR in ./main.ts 41:30
Module parse failed: Identifier 'isAndroid' has already been declared (41:30)
File was processed with these loaders:

• ../node_modules/@nativescript/webpack/helpers/android-app-components-loader.js
• ../node_modules/@nativescript/webpack/bundle-config-loader.js
• ../node_modules/@nativescript/webpack/hmr/hot-loader.js
• ../node_modules/ts-loader/index.js
  You may need an additional loader to handle the result of these loaders.
  |
  | import "@nativescript/core/bundle-entry-points";

    import { Application, isAndroid, isIOS } from "@nativescript/core";

| Application.on(Application.launchEvent, (args) => {
| if (isAndroid) {
...

When just importing _isAndroid_ from nativescript/core without using it, the build works fine and the app start correctly. But as soon as I try to use it anywhere (even just console.log(isAndroid ), the build fails on Android.

To Reproduce
Create a new nativescript app using the Hello World template (or use the sample app provided below) and add the following code to the main.ts:

import {Application, isAndroid, isIOS, LaunchEventData} from "@nativescript/core";

Application.on(Application.launchEvent, (args: LaunchEventData) => {
    if(isAndroid) {
    console.log("android app launched");
    } else if(isIOS) {
    console.log("ios launched");
    }
});

Application.run({ moduleName: "app-root" });

Expected behavior
The build should work correctly for Android as well.

Sample project
ns7_issue_app_ts.zip

[felixkrautschuk]

I also tried to import _isAndroid_ from @nativescript/core/platform (not from @nativescript/core), but the build fails with the same error message.

When importing the whole platform-module like this:

import * as platform from "@nativescript/core/platform";

Application.on(Application.launchEvent, (args: LaunchEventData) => {
    if(platform.isAndroid) {
        console.log("#################### ANDROID APP LAUNCHED");
    } else if(platform.isIOS) {
        console.log("#################### IOS APP LAUNCHED");
    }
});

... then the build works as expected and the app starts correctly on Android.

[Burgov]

same here. You can fix it for android by removing the import and saying declare const isAndroid: boolean, and then it'll work, but it'll fail for iOS.

However, you can use isIOS and it'll work fine for both platforms!

[plackowski]

something new?

[wendt88]

Same problem here, I resolved it:

import { Application } from '@nativescript/core';

const _isAndroid = !!Application.android;
const _isIOS = !!Application.ios;

works on both platforms, on macOS and windows