Migrate from jslint to eslint for the javascript linter

[timabbott]

jslint is pretty clearly no longer the preferred choice for javascript linter, and eslint has a pretty active plugin ecosystem which should make it easy to add new options.

Since the projects likely have different configurations by default, the way I'd want to do this project is to first replace jslint with eslint configured to check as close to the same rules as we have jslint doing (to minimize the amount of refactoring involved in switching), and then if we want to, we can incrementally improve the eslint configuration...

[timabbott]

This is probably a manageable task for someone new to the project, since an initial goal would be to get eslint to check for the issues we're checking with jslint and throw no errors (I'm sure there are guides on the internet for how to do this) and then we can go from there.

[timabbott]

Just noting that @trojan is planning to work on this.

[brainwane]

@trojan Are you still planning to work on this? If so, please speak up here by Wednesday the 21st. If not, I'd like to suggest it to a new contributor. Thanks!

[taranjeet]

@brainwane : You can assign this to a new contributor. Right now much busy at my workplace.

[timabbott]

This was fixed via #2246. While technically the description of this issue was about replacing jslint, the actual core goal was to integrate and add eslint so that we can start configuring more advanced linter rules; we can remove jslint now at our leisure.