Once the development process of an application or a feature is done, it is time to test it.
You should deploy your mobile applications to any device you want to support in order to check how it works on them. But during development, you don’t want to go through the deployment process every time you want to check if a new feature or fix works. Instead, you can run your application in a web browser, just like with web applications.
But mobile applications are not meant to work in every desktop browser. For example, Firefox usually renders mobile applications wrong. For mobile applications, you should use Chrome (or Chromium) instead. Or even better, connect a mobile device to the same network as your workstation, and access your application using the device’s web browser.
Bear in mind that, even if you access your application remotely from a mobile browser, hardware features are only meant to work after your application has been deployed, so you won’t be able to completely test you application until you actually deploy it and run it in a real device or emulator as a native application.