JavaScript has multiple ways to define a function so you sort of lose that getting the actual definition benefit.
on edit: I see someone discussed that you can grep for both arrow functions and named function at the same time and I suppose you can also construct a query that handles a function constructor as well - but this does not really handle curried functions or similar patterns - I guess at that point one is letting the perfect become the enemy of the good.
Most people grepping know the code base and the patterns in use, so they probably only need to grep for one type of function declaration.
on edit: I see someone discussed that you can grep for both arrow functions and named function at the same time and I suppose you can also construct a query that handles a function constructor as well - but this does not really handle curried functions or similar patterns - I guess at that point one is letting the perfect become the enemy of the good.
Most people grepping know the code base and the patterns in use, so they probably only need to grep for one type of function declaration.