How do you charge Joy-Cons without a Switch?

How do you charge Joy-Cons without a Switch? If the Joy-Con are removed from the Switch, they can be charged with the Charging Grip. That also has a USB-C connection, and plugging the cable into the Grip, which is sold separately for $29.99, will charge those controllers up.

If the Joy-Con are removed from the Switch, they can be charged with the Charging Grip. That also has a USB-C connection, and plugging the cable into the Grip, which is sold separately for $29.99, will charge those controllers up.