Question

If I have var foo = 'bar';, how do I get all the functions callable on foo, such as toUpperCase? It’s not an object, so Object.getOwnPropertyNames(foo) doesn’t work:

$ node
> var foo = 'bar';
undefined
> console.log(Object.getOwnPropertyNames(foo));
TypeError: Object.getOwnPropertyNames called on non-object
    at Function.getOwnPropertyNames (native)
    at repl:1:20
    at REPLServer.eval (repl.js:80:21)
    at repl.js:190:20
    at REPLServer.eval (repl.js:87:5)
    at Interface.<anonymous> (repl.js:182:12)
    at Interface.emit (events.js:67:17)
    at Interface._onLine (readline.js:162:10)
    at Interface._line (readline.js:426:8)
    at Interface._ttyWrite (readline.js:603:14)

katspaugh’s simple, elegant solution:

> console.log(Object.getOwnPropertyNames(foo.constructor.prototype));
[ 'constructor',
  'length',
  'toLowerCase',
  ... ]
undefined

Answer 1

The methods you want are on the String.prototype, the prototype of all strings, ruler of Valindor.

Object.getOwnPropertyNames('baz'.constructor.prototype)