Ruby's `include` in JavaScript/TypeScript

mixin.ts

function mixin(cls: Function, mod: Function) {
  const proto = {
    __proto__: Object.getPrototypeOf(cls.prototype)
  }
  Object.getOwnPropertyNames(mod.prototype).forEach(field => {
    if (field == 'constructor') return;
    proto[field] = mod.prototype[field]
  })
  Object.setPrototypeOf(cls.prototype, proto)
  return cls
}

declare global {
  interface Function {
    mixin(mod: Function): this
  }
}

Function.prototype.mixin = function (mod: Function) {
  return mixin(this, mod)
}

class Mod {
  foo() { console.log('Mod') }
}

interface A extends Mod {}
class A {
  static { this.mixin(Mod) }
  constructor() {
    this.foo()
  }
}

new A()