Getting all methods of an object - TypeScript version

methods.ts

type Obj = Record<any, any>

const isGetter = (x: Obj, name: string) => Boolean((Object.getOwnPropertyDescriptor(x, name) ?? {})?.get)
const isFunction = (x: Obj, name: string) => typeof x[name] === 'function'
const deepFunctions = (x: Obj): string[] =>
  (x && x !== Object.prototype &&
  Object.getOwnPropertyNames(x)
    .filter(name => isGetter(x, name) || isFunction(x, name))
    .concat(deepFunctions(Object.getPrototypeOf(x)) || [])) || []

const distinctDeepFunctions = (x: Obj) => Array.from(new Set(deepFunctions(x)))
const getMethods = (obj: Obj) => distinctDeepFunctions(obj).filter(
  name => name !== 'constructor' && !~name.indexOf('__'))