I recently read a code like this one in a react project:
export const funcName = (
arg1: Type1,
arg2: Type2,
...
argN: TypeN,
) => async (dispatch: Dispatch) => {
// function body
// ..
};
and I can't understand the double arrow (() => async => {}) syntax.
Can some tell me what is happening here? Thanks
What this is doing is saying you're returning a function that takes Dispatch. Most likely this is used for Redux in some way.
This is also called "higher order functions" which are functions that take in some arguments and return a function. In this case, an async function.
To be more clear, the function inside does not get executed when you call funcname, it just gets built. The async function has access to the args passed to funcname though, so it helps build it.
If you convert that to function syntax it may be more understandable:
export function funcName (
arg1: Type1,
arg2: Type2,
...
argN: TypeN,
) {
return async function takesDispatch(dispatch: Dispatch) {
// function body
// ..
}
}
So it gets called as
let takesDispatch = funcName(arg1, arg2, ... args)
await takesDispatch(dispatch)
