# Android browser's about:debug, what do those settings do?

I have just found this hidden setting:

1. Open Stock browser (Not Chrome on ICS. about:debug doesn't work in Chrome. Use remote debugging instead.)
2. In the address bar, type about:debug, nothing should happen, there will be no confirmation screen or flashing green box telling you that you've done anything.
3. However, there should now be a few new options in the browser's Settings page.

(Click image to enlarge)

In Menu > More > Settings:

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In Menu > More, there is also:

(Click image to enlarge)

probably there are other new menus showing up that I haven't noted and the menus are very likely to be version specific.

While, I understand some of these settings, there are many of these settings that I don't understand, like where can I find the Javascript Console, what is being traced, what light touch and nav cache dump does, where do the dump files being saved to, what are the valid JS (Javascript?) flags, etc.

I find it difficult to Google what these setting do. I'd like help from others to play/experiment/Google with about:debug and write up what these settings do. Any bits of info you can gather is helpful.

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V8 is part of WebM video, isn't it? –  Al E. Feb 15 '11 at 17:31
@Al Everett: as far as I know, V8 is the javascript engine used in Chrome and by Android's Browser since Froyo(?) and above. –  Lie Ryan Feb 15 '11 at 17:36
I'm misremembering something, then. Happening a lot today. –  Al E. Feb 15 '11 at 18:23
@Al Everett: You're probably referring to VP8 Codec, which is part of WebM: en.wikipedia.org/wiki/VP8 –  Lie Ryan Feb 15 '11 at 20:01
Ah, yes. Of course. Thanks. –  Al E. Feb 15 '11 at 20:04

Javascript Console is this thing:

For some reason, the "Show JavaScript console" bar will only show up in android.com website. Not sure whether the Syntax Error triggers the console or if there is another reason why it shows in android.com and none of the other sites I've been checking.

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I can confirm that the console option shows up only when a JS error is triggered. Here's a simple jsbin that triggers an error (and loads a lot faster): jsbin.com/owecey –  Jörn Zaefferer Jan 21 '12 at 11:54
I am unable to see the console on my HTC thunderbolt after doing about:debug and going to jsbin.com/owecey . Does anyone have any suggestions? My Android Version is 2.3.4, and my HTC Sense Version (if it matteres) is 2.1 –  bnieland Apr 27 '13 at 12:20

The about:debug menu on the HTC Desire HD has an option under Menu > More > Settings called "Enable GEP Zoom". This turns off HTC's Text reflow feature and uses the default Google zoom.

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UAString will change the User Agent String that Browser sends when requesting page. User Agent String is a short string (text) that the Browser sends to identify itself to the server. Many websites tries to detect the browser that is connecting to the website, and will serve different pages that is optimized for the browser. One of the most common method for such browser detection is by checking the UAString. The UAString setting basically spoofs the UAString and makes the server believes that Android Browser is really another browser.

There are three options for UAString:

• Android (default)
• Desktop
• iPhone

The Android UAString is the default UAString that is sent by Android, websites may serve a mobile version of their site when detecting this UAString. Desktop can be used to force the server to serve the Desktop version of the site instead of serving up mobile-friendly version. On the other hand, iPhone UAString can be used if you know that the server have a mobile friendly version optimized for iPhone, but is not detecting Android as a mobile phone and so is falsely serving a desktop version.

For example, this is what http://www.useragentstring.com detects when my Samsung Spica used the various settings:

• when using Android: Mozilla/5.0 (Linux; U; Android 2.2.2; en-au; GT-I5700 Build/Froyo) AppleWebkit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
• when using Desktop: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_7; en-us) AppleWebkit/530.17 (KHTML, like Gecko) Version/4.0 Safari/530.17
• when using iPhone: Mozilla/5.0 (iPhone; U; CPU iPhone OS 3_0 like Mac OS X; en-us) AppleWebkit/528.18 (KHTML, like Gecko) Version/4.0 Mobile/7A341 Safari/528.16
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On the Desire HD you can also choose from "iPad" and "Manual". Manual pops up a text box so you can pretend to be any browser you like. –  Matt H Feb 15 '11 at 18:00
You can access this setting directly by entering about:useragent in the url bar. On my Smsung Galaxy S I have a choice of Android, Iphone, Desktop, Lismore, Custom –  fearoffours Mar 16 '11 at 13:13
CyanogenMod 7 has quite a few options for UAString, but it's available from the menus & you don't need about:debug. –  Broam Apr 9 '12 at 20:18
There are more than just those three user agents. The box that displays them, in horizontal mode, only shows 3, but in vertical mode, shows many more. The box does not have scroll bars :/ atleast on 2.2.3 Webkit based stock browser. –  cde Dec 14 '14 at 5:11

Single Column Rendering causes Browser to use a different layouting algorithm.

I'm not exactly sure what the algorithm's logic is, but it seems to be an attempt to force a website that were not designed for mobile to render in a single column for easier viewing on small screens. Not sure if that's the case though, since enabling single-column view breaks the layout of android.stackexchange.com and disables text reflow, which makes reading much more painful than when using the default layouting. It seems this feature is not used for a reason, I cannot find a single web page that looks better when rendered in Single column rendering mode; even pages optimized for mobile views looks better in default than in Single-column mode.

The following are some screenshots comparing default and single-column rendering, the screenshot on the left are in no-single-column the screenshot on the right are the same page with single-column:

android.stackexchange.com

android.com

Wikipedia today's front page Mobile View:

Wikipedia today's front page disable Mobile View:

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