Last week a colleague introduced me to a handy Chrome Extension called
Sight that allows syntax highlighting in your browser and "makes reading code on the browser a joy".
After using it for few days I have to admit that it does make javascript a lot easier on the eye. It has optional line numbers and supports syntax for about 35 different languages.
Sadly it doesn't support view-source highlighting, but apparently it's next on the to-do list and is still worth installing in it's current state.
If you're using Chrome you can get the extension from here
https://chrome.google.com/webstore/detail/epmaefhielclhlnmjofcdapbeepkmggh
