no-unused-vars breaks the convention

[bisubus]

Current no-unused-vars rule forces to use _ parameter name to identify it as unused. It clashes with jQuery and forces a dev to destroy parameter name, even if it's temporary unused. The existing convention is to start the parameter with an underscore, like _foo, i.e. it should be ^_, not ^_$. The convention is followed by TS itself and other tools.

It's a great default ruleset in other respects.