jQuery: $(this) vs $(event.currentTarget)

When working with jQuery in ES6 you have to pay particular attention to `$(this)` in event handlers. Using `$(this)` in ES5 is quite popular to access the DOM element of the event handler. In ES6 the code breaks if you switch from function to arrow function syntax:

``` js
// works:
$selector.on('click', function() {
$(this).hide();
});

// doesn't work:
$selector.on('click', () => $(this).hide());
```

Instead you have to access the DOM element via `event.currentTarget`:

``` js
// works:
$selector.on('click', ev => $(ev.currentTarget).hide());
```

IMO the main problem is that you can accidentally break code by just switching from `function` syntax to arrow functions. I'm aware that this problem is not exclusive to jQuery but since `$(this)` is so widely used in jQuery code, imo it wouldn't be the badest idea idea to add this to the list of bad styles.

What do you think?

The issue discusses jQuery event handlers, `$(this)`, `event.currentTarget`, and arrow functions, but names no repository file, test, or entry point. First determine whether the style guide should document this as a bad style, then identify the appropriate guidance location and define the expected wording before making any change.

Written by the indexing model from the issue text.