Chrome and Mocha Global Leaks - google-chrome

Question

I have the following extremely simple Mocha / Chai test:
describe('main tests', function () {
var expect = chai.expect, something = null;
before(function () {
something = 0;
});
it('should equal 0', function () {
expect(something).to.equal(0);
});
});
This fails in chrome with the following output:
Error: global leaks detected: css, cssFile, cssRule
In both Firefox and Safari, it passes with no problem.
There was another global variable defined by Google's own Screen Capture extension. Upon disabling that extension Mocha only complained about css, cssFile, and cssRule being global leaks.
I checked and these variables are not defined in Safari or Firefox, so obviously something in Chrome or one of my Chrome extensions is defining these three variables. Is there any way to figure out which extension is defining these variables short of disabling and reenabling all of them in sequence?

Answer 1

The best solution for your problem is not some JavaScript snippet, but the source code of your installed extensions.
Visit the Extensions sub-directory of your Chrome profile (locations below).
Use a tool to recursively search for the term.
For example, using the grep command: grep -r 'cssFile' (available for Linux, Mac and even Windows).
Default locations for your profile's Chrome extensions
Windows XP:
Chrome : %AppData%\..\Local Settings\Application Data\Google\Chrome\User Data\Default\Extensions\
Chromium: %AppData%\..\Local Settings\Application Data\Chromium\User Data\Default\Extensions\
Windows Vista/7/8:
Chrome : %LocalAppData%\Google\Chrome\User Data\Default\Extensions\
Chromium: %LocalAppData%\Chromium\User Data\Default\Extensions\
Linux:
Chrome : ~/.config/google-chrome/Default/Extensions/
Chromium: ~/.config/chromium/Default/Extensions/
Mac OS X:
Chrome : ~/Library/Application Support/Google/Chrome/Default/Extensions/
Chromium: ~/Library/Application Support/Chromium/Default/Extensions/

Answer 2

Well, I just did the disable all extensions thing. Chrome Sniffer appears to be the culprit. Specifically in the following code (detector.js):
for (t in cssClasses) {
// snipped for brevity
for(css in cssClasses[t]) {
// snipped for brevity
for(cssFile in document.styleSheets) {
for(cssRule in document.styleSheets[cssFile].cssRules) {
// snipped for brevity
}
}
}
}
That will leak t, css, cssFile, and cssRule into global scope. Looks like I'm not the first to notice this: https://github.com/nqbao/chromesniffer/pull/51
If anybody wants to answer with how I could have avoided the manual process I will accept your answer.