Tag: javascript

Debugging Web Apps on Android’s Mobile Browser – Part 2

In addition to the suggestions listed in Part 1, I forgot to mention one more tool. There is a lesser known browser that can be quite handy for debugging: Firefox mobile. This relatively unknown sibling of the full-blown desktop browser actually has a fairly nice, built in debugger. The one major caveat is that it doesn’t work as well as the native browser for HTML5, CSS3 and some JavaScript, but it may be just the tool you need for some quick debugging, on-the-fly. Besides it fits in your pocket along with your other mobile apps, and you don’t need Logcat.

Step 1 – place your finger in the middle of the screen and drag it to the left. Click the gears icon at the bottom right of the screen.

Step 2 – In the upper right hand corner of the next screen, click the bug icon

Step 3 – Scroll down the datagrid to view errors.

Debugging Web Apps on Android’s Mobile Browser

For some unknown reason, Google did not include a debugger in their native browser, at least for versions up to v2.3.x. I don’t have a phone that supports a version greater than that, yet, so I can’t speak about the latest releases. Unfortunately this can be a huge productivity killer. The good news is there is a solution – you can debug the native Android browser using what’s called the DDMS, or Dalvik Debug Monitor Server, and the ADB, or Android Debug Bridge. I can also tell you this works great.

Yes, it’s true that JavaScript development forces you to have an armada’s worth of tools, tricks, libraries, phones and browsers. This is just another hammer to place into your growing toolkit. Debugging via ADB was good news for me since I do native Android development and I already have the software installed when I installed the full Android SDK. If you don’t do native development then it’s a real pain.

But, if you want to do your best to deliver bug free apps, then your best bet is to install at least ADB. I believe, but I’m not 100% certain, that you can this without having to install Eclipse along with the entire Android SDK. Yes, I agree that installing the entire SDK would seem entirely ridiculous and complete overkill for mobile web development, especially if you are not using Eclipse as your primary IDE. I’m aware that in the past I’d seen a few stand-alone versions of this floating around for both Windows and Linux. I’m not even remotely certain about Mac’s. If you do know something about this, then I encourage you to please post a comment.

How to use ADB. My suggestion, once you’ve installed it, is to filter by the tag “console” if you are using Android v2.x and above.  Instructions on how to do filtering can be found in the ADB link below and scroll towards the very bottom of the page.

Caveat: You will have to install the Android USB device driver on your machine in order for ADB to work.  And, you will also have to have a USB cable that will connect your device to your dev machine. The drivers are different for every device. I’ve included a link to Google’s device drivers below. On a related note, for several of my Motorola Androids I had to go directly to the Motorola website to find a device driver that finally worked.

Another Possibility – Adobe Shadow! You should also be aware of a very cool development from Adobe called Shadow. As of today, I believe you can still download it for free from Adobe labs. I mention this last because, well…I haven’t tried it out. However, my good friend Kevin Hoyt, from Adobe, says it’s very, very promising. And, it’s supported on both Mac and Windows. As I write this I’m thinking that I really do need to download it and test drive it. If you have tried it, then post your thoughts…don’t by shy!

References:

Adobe Shadow + sneak peak video

Google’s ADB

Android Device Drivers

Google’s Guidelines for Web app developers

The problem with JavaScript Obfuscators and Minification – Tracking down errors

JavaScript obfuscators and minifiers do their job well. In fact, some obfuscators have anti-debugging features. However, if you are a legitimate developer building applications against one of these libraries, chances are you’ve gotten an indecipherable error such as “z=null line 14300” and it brings your development efforts to a halt. Error messages like this provide no useful information on what the problem really is, or give any hints on how you might be able solve it. You’ve probably even looked at the jumbled source code in a last ditch attempt to make some sense out of the error. And, whether it’s your own library or a mainstream ones as jQuery or Dojo, it doesn’t matter. The amount of productivity lost because of these errors in probably very large, not to mention the frustration it causes.

I hope the the developers of these obfuscators are reading this…because I have a proposed solution to the problem.

Now, I want to start out by mentioning that I fully understand why obfuscators exist for reasons such as source code protection and decreasing download size. What I propose takes this fully into account, yet makes your library developer friendly in a secure way:

During the obfuscation process create an index file that maps each variable, function and class to a real line number and store this file in a web folder.  Then create a small html file that lets you search the index and return the real line number. Provide an option for return the variable, function or class name, too.

The concept is that if there is an error, like the  “z=null line 14300” I mentioned above, developers can then at least have some hope of narrowing down the general area of the code where it might be occurring.

The bonus is, if you own an obfuscated commercial library, now your tech support people can also look up the general area where a customer might be having a problem. For security reasons you don’t have to share the index file, But, even then, there isn’t enough information in it to de-compile the library. Now, if I post my error to the forum:  What is “z=null line 14300”? Tech support will be able to tell me that I’m missing a custom property on a widget’s HTML DIV element. It’s a win-win situation.

What do you think?