tmhao2005I recently ran into the issue as following:
const actions = {
call: (num: number) => {
// todo
},
speak: (text: string) => {
// todo
},
}
// I'm going to create a function which can pass the action
// and its corresponding argument as following:
doThings('call', 911);
doThings('speak', 'hello');
// so here the simple implemenatation
type Actions = typeof actions;
function doThings<T extends keyof Actions>(p0: T, ...[p1]: Parameters<Actions[T]>) {
const action = actions[p0];
// error!
// Argument of type 'string | number' is not assignable to parameter of type 'never'.
action(p1);
}
As we can see, it has a typing issue as the comment. I quickly searched for solution, then I ended up following up this issue which was open long ago https://github.com/microsoft/TypeScript/issues/30581.
Looks like we haven't yet had a good solution for the issue though. I eventually came up with a solution after reading a few solutions/hackarounds from comments as following:
// create arguments map
type ArgsMap = {
call: [num: number, message: string];
speak: [message: string];
};
// this is a key where we have to define the type for the object
const actions: {[K in keyof ArgsMap]: (...p: ArgsMap[K]) => void} = {
call: (num, message) => {
// todo
},
speak: (text) => {
// todo
},
}
// eventually the function signature
function getAcion<K extends keyof ArgsMap>(name: K, ...p: ArgsMap[K]) {
const action = actions[name]
// works!
action(...p)
}
