Introduction

apk.js runs Android APKs in the browser with plain JavaScript. It reads an APK, executes the application bytecode, and draws the resulting UI on a Canvas. There is no device, emulator or native library involved.

How it works

An APK is a zip archive. apk.js pulls five things out of it:

1. classes.dex — application bytecode, executed by the DEX interpreter.
2. AndroidManifest.xml — binary AXML, describing the package, activities and theme.
3. resources.arsc — the resource table, resolving IDs to strings, colors and file paths.
4. res/ files — layouts and drawables, also binary AXML.
5. assets/ files — application assets, served through the runtime.

The interpreter calls into a Canvas-backed implementation of the Android Framework. When the app calls setContentView, inflates a layout or measures a view, that call lands in the framework subset, which knows how to paint to a canvas.

What it supports

The project targets small and medium Java/Kotlin apps. The sample hello-dex.apk exercises counters, text input, dynamic views, progress bars, shape drawables, Build info, reflection and multi-activity navigation.

Real apps work too. image-debug/devinfo.png is a render of a hardware-info app running through the interpreter.

Where to go next

• Quick start — get the demo running.
• Embedding — put a simulator on your own page.
• Architecture — how the pieces fit together.