It is needed if we use the noImplicitAny switch in the tsconfig.json file.
Otherwise the typescript compiler won't compile it.
Error messages caused by lack of explicit return types:
node_modules/perfect-scrollbar/perfect-scrollbar.d.ts(16,3):
error TS7010: 'initialize', which lacks return-type annotation, implicitly has an 'any' return type.
node_modules/perfect-scrollbar/perfect-scrollbar.d.ts(17,3):
error TS7010: 'update', which lacks return-type annotation, implicitly has an 'any' return type.
node_modules/perfect-scrollbar/perfect-scrollbar.d.ts(18,3):
error TS7010: 'destroy', which lacks return-type annotation, implicitly has an 'any' return type.
Gergely Grusz