How can I add optional named parameters to a TypeScript function parameter? -

How can I add optional named parameters to a TypeScript function parameter? -

i'd able define method accepts arrow function parameter. function parameter should able define 0 or more named parameters of own. how can this?

i've tried

public dosomething(fn: () => any) {}

and

public dosomething(fn: (...args) => any) {}

but both throw "supplied parameters not match" error when seek phone call follows:

dosomething((test: string) => {})

(note type , number of parameters function may vary on each usage, can't set type(s) on original method.)

i can supply parameters using ...args syntax within passed function, able type , name specific parameters.

is there way this?

two options. reasons type safety. if work through statements below should clear.

fix callback:

if function expects phone call callback 0 or more arguments, callback must okay (i.e. have optional arguments) i.e.

function dosomething(fn: () => any) {} // arguments need optional dosomething((a?:string)=>{});

same :

function dosomething(fn: (...args:string[]) => any) {} // arguments need optional dosomething((a?:string)=>{}); fix callback signature:

if going phone call callback 'n' arguments, specify names in signature. callback take or ignore these. eg. callback ignores them:

// specify number of arguments function dosomething(fn: (ar1:string,arg2:string) => any) {} dosomething(()=>{});

typescript