Debugging utility for enumerating function methods on a class instance in Javascript

list-all-methods-of-class.js

function getMethods(obj) {
  const excludeBuiltIns = Object.getOwnPropertyNames(Object.prototype)
  let properties = new Set()
  let currentObj = obj
  do {
    Object.getOwnPropertyNames(currentObj).map(item => properties.add(item))
  } while ((currentObj = Object.getPrototypeOf(currentObj)))
  return [
    ...properties.keys()
  ].filter((item) => {
    return !excludeBuiltIns.includes(item) && typeof obj[item] === 'function'
  })
}

class Thing {
  foo() {}
}

var thing = new Thing()
console.log(thing)
// Thing {}
console.log(getMethods(thing))
// ["foo"]