Ad block Plus debugging, undertsanding code base - javascript

I am working on a project which involves ad-detection. I wanted to leverage ad block plus code. But I am struggling with understanding it.
I am using adblock plus for chrome and using chrome debugger to step through the code, but whatever breakpoints i set inside most of the javascript files, the control is not getting there. I am only able to see the control going to include.preload.js. I have added the source folder to work space.
Also content script is showing only a few files and breakpoint set in inlcude.preload.js in content scripts is working, but breakpoints set anywhere else dont seem to get hit, not even if they are set in source tree.
Any pointers will be very helpful. I am struggling as I am new to this domain. If there are any books/resources to help understand the working of ad block plus better, please suggest. Thanks in advance.

include.preload.js and include.postload.js only contain the code that's being injected into the page. The core code of the extension is running in its background page which you can debug like this:
Go to chrome://extensions
Check the "Developer mode" checkbox in the top-right corner
Click on the "Background page" link underneath the Adblock Plus entry

Related

How to see all of scripts on Chrome's dev tool?

Hello. I'm fixing some scripts from website which made by other one.
First I should look all of existing scripts but chrome dev tool doesn't show all of the source code in script tag.
I tried to copy it but still copied with "...".
I searched some keyword from the whole webpage code and I can find it in hidden part so maybe Chrome get a full script but just not showing to me.
How can I see all of scripts?
Double click the ellipsis or single click on the arrow to expand the script region:
You could also try right click and copy the outer HTML or you can edit the node as HTML inline... Explore the other options available to you in the context menu:
NOTE: If you are editing an existing web page you should probably start with the source code for the site and use an HTML code editor to edit the page and scripts, otherwise any changes you make wont be fixing the site for all users, the changes will be just for you.

Getting the contents of Chrome's console with JavaScript

First time poster. Currently trying to work on a project but I am having an issue with iframes. I'm making an extension for Chrome, and part of its functionality right now is to be fetching any shapes/borders on a page. Unfortunately, that also includes ones within iframes. I'm currently stuck because I cannot get around security policies from Cross-Domain sources.
I was wondering, however, if it is possible to create a function that displays what the Chrome console does when I hit "inspect element" on a page... I tried to make a console function called "save" that would automatically download a file of anything output to the log, but the output for the iframe's HTML is blank except for its tag...
When I am inspecting an element on the page, I can see the contents of that iframe just fine. Is there anyway to just get the actual text from Inspect Element and store that? I know this may be silly, but I genuinely have no idea. I am pretty new to JavaScript. I just need to match up script tags for shapes for part of the extension's functionality.
I'm assuming that this is going to end up being impossible, but I figured I'd ask. I'm also assuming that this inspect element functionality is something that only the browser can work with. But hey, maybe there's a way. Thanks for any help.

Website wont show on IE once I activate scripts. Everything is missing except for the background

So, I've been creating a site based off a template. The site used to work on IE, but I'm afraid that I have made changes since then that causes everything to go haywire. When first visiting the site my grids and alignments are all off and most of the javascript doesnt work. When I activate scripts and ActiveX all of the elements of the site are invisible except for the background. Though, I can still see the source in this instance.
The site (for now) is: http://www.escroft.com/index(main).html
If the site is not displaying when you turn scripts on, you probably have a script error. Open your developer tools with F12, and reload the page; the console should show you what errors you have, and then you're on your way to fixing them.

Editing in the Chrome debugger

How do I "dynamically" edit JavaScript code in the Chrome debugger? It's not for me, so I don't have access to the source file. I want to edit code and see what effects they have on the page, in this case stopping an animation from queuing up a bunch of times.
I came across this today, when I was playing around with someone else's website.
I realized I could attach a break-point in the debugger to some line of code before what I wanted to dynamically edit. And since break-points stay even after a reload of the page, I was able to edit the changes I wanted while paused at break-point and then continued to let the page load.
So as a quick work around, and if it works with your situation:
Add a break-point at an earlier point in the script
Reload page
Edit your changes into the code
CTRL + s (save changes)
Unpause the debugger
You can use the built-in JavaScript debugger in Chrome Developer Tools under the "Scripts" tab (in later versions it's the "Sources" tab), but changes you apply to the code are expressed only at the time when execution passes through them. That means changes to the code that is not running after the page loads will not have an effect. Unlike e.g. changes to the code residing in the mouseover handlers, which you can test on the fly.
There is a video from Google I/O 2010 event introducing other capabilities of Chrome Developer Tools.
You can use "Overrides" in Chrome to persist javascript changes between page loads, even where you aren't hosting the original source.
Create a folder under Developer Tools > Sources > Overrides
Chrome will ask for permission to the folder, click Allow
Edit the file in Sources>Page then save (ctrl-s). A purple dot will indicate the file is saved locally.
This is what you are looking for:
1.- Navigate to the Source tab and open the javascript file
2.- Edit the file, right-click it and a menu will appear: click Save and save it locally.
In order to view the diff or revert your changes, right-click and select the option Local Modifications... from the menu. You will see your changes diff with respect to the original file if you expand the timestamp shown.
More detailed info here: http://www.sitepoint.com/edit-source-files-in-chrome/
Chrome Overrides
Open the JS file in the sources panel.
Right Click on script src URL > Reveal in Sources panel
Make sure "Enable Local Overrides" is checked.
Right Click anywhere in the JS file > Save for overrides
All Set!
Just edit the file, and save with CMD/CTRL + S. Now whenever you refresh the page, it'll use the modified file. (As long as the filename remains the same)
You'll know it's working if you see a purple dot in the file icon.
Place a breakpoint
Right click on the breakpoint and select 'Edit breakpoint'
Insert your code. Use SHIFT+ENTER to create a new line.
Pretty easy, go to the 'scripts' tab. And select the source file you want and double-click any line to edit it.
If its javascript that runs on a button click, then making the change under Sources>Sources (in the developer tools in chrome ) and pressing Ctrl +S to save, is enough. I do this all the time.
If you refresh the page, your javascript changes would be gone, but chrome will still remember your break points.
As this is quite popular question that deals with live-editing of JS, I want to point out another useful option. As described by svjacob in his answer:
I realized I could attach a break-point in the debugger to some line of code before what I wanted to dynamically edit. And since break-points stay even after a reload of the page, I was able to edit the changes I wanted while paused at break-point and then continued to let the page load.
The above solution didn't work for me for quite large JS (webpack bundle - 3.21MB minified version, 130k lines of code in prettified version) - chrome crashed and asked for page reloading which reverted any saved changes. The way to go in this case was Fiddler where you can set AutoRespond option to replace any remote resource with any local file from your computer - see this SO question for details.
In my case I also had to add CORS headers to fiddler to successfully mock response.
Now google chrome has introduce new feature. By Using this feature You can edit you code in chrome browse. (Permanent change on code location)
For that Press F12 --> Source Tab -- (right side) --> File System - in that please select your location of code. and then chrome browser will ask you permission and after that code will be sink with green color. and you can modify your code and it will also reflect on you code location (It means it will Permanent change)
Thanks
Just like #mark 's answer, we can create a Snippets in Chrome DevTools, to override the default JavaScript. Finally, we can see what effects they have on the page.
here's a gentle introduction to the js debugger in chrome that i wrote. Maybe it will help others looking for info on this: http://meeech.amihod.com/getting-started-with-javascript-debugging-in-chrome/
you can edit the javascrpit files dynamically in the Chrome debugger, under the Sources tab, however your changes will be lost if you refresh the page, to pause page loading before doing your changes, you will need to set a break point then reload the page and edit your changes and finally unpause the debugger to see your changes take effect.
I was looking for a way to change the script and debug that new script. Way I managed to do that is:
Set the breakpoint in the first line of the script you want to change and debug.
Reload the page so the breakpoint is being hit
Paste your new script and set desired breakpoints in it
Ctrl+s, and the page will refresh causing that breakpoint in first line to be hit.
F8 to continue, and now your newly pasted script replaces original one as long as no redirections and reloads are made.
Chrome DevTools has a Snippets panel where you can create and edit JavaScript code as you would in an editor, and execute it.
Open DevTools, then select the Sources panel, then select the Snippets tab.
https://developers.google.com/web/tools/chrome-devtools/snippets

Firefox Firebug Extension - Freeze Javascript Feature?

How can I freeze Javascript in firebug so that i can inspect the changes made by it in the html? If for example i have a jQuery rollover effect and i want to inspect the html code in that point in time.
I believe Dreamweaver CS4 has this feature titled freeze javascript and live code. Is there a free equivalent either in Firebug or another Firefox extension?
By "freeze" I assume you mean debugging, and yes, Firebug definitely has that.
First you have to go into the Script tab on Firebug. If Script is disabled on the site, enable it.
Now, go to the dropdown and select which JavaScript file you want to debug. This is typically either the page itself with inline JavaScript, or a linked page. Find the line of code you want to freeze on, and click to the left of the line numbers. You'll see a red dot appear - this dot denotes that the code will freeze there during execution. Once the code is there, you can access the current HTML by going to the "HTML" tab. You'll also see the icons in the top-right corner of Firebug's Script pane light up, allowing you to either continue execution, step over, step into, or step out of each line of code, observing HTML changes for each line executed.
Note that Firebug lets you step through code line-by-line, which means that minimized JavaScript files (wherein all the code is compacted onto one line) are absolutely awful for debugging, because you can't tell where Firebug is. So for debugging purposes, I highly recommend getting the non-minimized versions of files.
If you need more help, I suggest checking out the Firebug documentation, which has some good guides.
Break on mutate (the pause button when the html tab is selected) is the closest thing I can find to this feature. It will pause the next time something is changed. It's just one off of what you want, but could be useful.
not exactly firefox function, but appears close enough (at least in the way I understand the question):
Get CheatEngine
Open firefox process
Check "enable speedhack"
Set speed to 0
Apply
All scripts are now effectively paused
You can test this on a javascript clock here.
I'm kind of dissapointed that noone has created a plugin for firefox, which would do the same.
In the Script tab of Firebug, you can set break points in Javascript that will allow you to step through code, set watches, and do other things you would in other debuggers. You can also switch to the HTML tab and see what changes have been made while Javascript is "frozen."
In Firebug, go to the script tab. On the top, you can see:
Inspect | all | <filename>
Click on to choose the file that contain the javascript you want to track. Once you have selected your file, click on a line number to put a brea kpoint (a big red dot will appear).
You can put several break points in different files. The break point will not disappear if you refresh the page (F5).
This tutorial should help you as well.

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