Yes, that is plural… Debugging Environments. Due to the cross-platform nature and PhoneGap’s leveraging of native web views for each platform, debugging PhoneGap applications can sometimes be tricky. Here are some tips that will make this significantly easier.
The PhoneGap Emulator
The PhoneGap Emulator is my primary development/debugging tool for all PhoneGap apps. It is a browser-based emulator leveraging the Google Chrome browser and the Ripple Emulation Environment. The PhoneGap Emulator runs inside of Google Chrome, and provides emulation of PhoneGap’s core APIs. Since it is built on top of Chrome, it enables you to leverage Chrome’s Developer Tools, which in my opinion are second to none for web/application development. This is a highly-productive developer environment.
PhoneGap Emulator in Google Chrome
Here’s why I like the PhoneGap/Ripple/Google Chrome development environment:
First, this combination enables you to emulate most core PhoneGap APIs without leaving the desktop environment. It enables you to test various APIs including geolocation (with simulated locations), device events (deviceready, back, etc…), sensor events (accelerometer, compass), and even let’s you test with different device aspect ratios – all without having to push anything to an actual device. This saves a lot of time in development iterations. You can read about the supported Ripple emulator features here.
Second, Chrome’s Developer Tools are awesome. Here are just a few things that you can do while developing/debugging your app, live within the emulation environment:
Analyze all resources consumed by your app, via the resources panel. This includes all scripts, images, html files, cookies, etc… it even includes insight into any local data stored via PhoneGap’s local storage database (WebSQL implementation).
View/query all local databases within your app. You can write your own queries to view/alter data in the WebSQL database. Thanks to Ray for sharing this, it’s not immediately intuitive.
Debugging Local Storage Databases in Chrome with SQL
Analyze network requests/utilization via the network panel.
Debug JavaScript with the Scripts/Sources Panel. You can set breakpoints in JS execution, inspect & alter values in JS objects in-memory, and view details and line numbers for any exceptions that occur.
Monitor function execution time, memory consumption, event listeners, and frame rendering time via the timeline panel.
Use the console to monitor console.log() statements, inspect properties of objects in memory, or execute arbitrary JavaScript whenever you want.
The PhoneGap Emulator enables developers to be extremely productive with development, however I cannot emphasize enough that on-device testing is critical for having a successful app. On-device testing can expose performance problems or browser rendering variances that you may not notice in the emulator environment.
