difference typescript/explicit-function-return-type vs typescript/explicit-module-boundary-types

[mesqueeb]

What's the difference between

• typescript/explicit-function-return-type
• typescript/explicit-module-boundary-types

[KieranP]

My understanding is that typescript/explicit-function-return-type checks all functions (declarations, expressions, and arrow), whereas typescript/explicit-module-boundary-types only deals with exports from a module.

typescript/explicit-module-boundary-types can be used to make TypeScript faster. If all module exports have explicit return types, TypeScript doesn't need to keep crawling up the module tree to infer it; with explicit typing it can instantly return it when you reference it. It applies to functions, variables, classes; anything exported from a module. With this check enabled, they must have an explicit return type.

On the other hand, typescript/explicit-function-return-type only operates only on functions, and requires explicit return typing for all functions, whether they are exported or not. This makes things a lot stricter, but also makes code more verbose (because TS no longer infer types).