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A tool for displaying code coverage of js files in the browser

Note. The current implementation is more 'proof of concept' and - ironically - totally untested.

The general idea is to convert the js into a format that will track which lines are executed (like JSCoverage) - though instead of doing this server side, this script does the conversion in the browser on page load.


Include your js files with the type of 'text/x-cov-javascript' and then include jscov.js.

<script src="yourcode.js" type="text/x-cov-javascript" charset="utf-8"></script>
<script src="jscov.js" type="text/javascript" charset="utf-8"></script>

This will request 'yourcode.js' via xhr, add markers to the code and re-insert it into a new script tag.

Including this file also gives access to a hacky ui for displaying the files and their coverage, once you've tested your code, call _$; to display list the js files and their code coverage

current limitations

  • This currently won't work through file: protocol.
  • The instrumentation (adding markers) is massively basic, it might miss sections or even break stuff.
  • document.scripts won't work in FF < 9.

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