Define a function with a prototype chain

Question

Suppose I have an object X defined as

var X = function () {};
X.prototype.doSomething = function () {};
X.prototype.doSomethingElse = function (         


        

Answer 1

No, it is not possible (in a standard way). Every possibility to create a callable object (i.e., a function) will create one inheriting from Function.prototype¹; and you can't change the [[prototype]] of an object afterwards².

See also:

• create function in javascript with custom prototype
• Can you create functions with custom prototypes in JavaScript?
• Is it possible to create a function with another prototype than Function.prototype?
• Can a JavaScript object have a prototype chain, but also be a function?
• Custom prototype chain for a function
• Correct prototype chain for Function (for some internals)

_{1: OK, ES6 allows us to subclass Function. But that's not as useful as it sounds.
2: Since ES6, you can use Object.setPrototypeOf.}