The negation is effectively just a cast to boolean in that situation. If the value changes from truthy to not-truthy or vice versa, then the effect will run aga

The negation is effectively just a cast to boolean in that situation. If the value changes from truthy to not-truthy or vice versa, then the effect will run again, otherwise it won't. Based on the name, it seem like onClickOutside will always be a function, so always truthy, so it's effectively the same as just leaving it out of the dependency array.