Explicit final argument in TypeScript

Is it feasible to define a function in TypeScript 2.7.2 and above with variable parameters, but ensuring that the final parameter has a specific type?

I am attempting to craft an ambient TypeScript declaration for a JavaScript library that utilizes functions with changing parameters, yet requires the last parameter to consistently be a predetermined callback function.

Answer №1

In order to effectively handle different scenarios, it is necessary to implement multiple overloads for the function.

declare function bar(param1: any, callback: () => void): void;
declare function bar(param1: any, param2: any, callback: () => void): void;
declare function bar(param1: any, param2: any, param3: any, callback: () => void): void;
// ...
declare function bar(...args: any[]): void;

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