How to get a JavaScript object's class?

Question

I created a JavaScript object, but how I can determine the class of that object?

I want something similar to Java\'s .getClass() method.

Answer 1

This getNativeClass() function returns "undefined" for undefined values and "null" for null.
For all other values, the CLASSNAME-part is extracted from [object CLASSNAME], which is the result of using Object.prototype.toString.call(value).

getAnyClass() behaves the same as getNativeClass(), but also supports custom constructors

function getNativeClass(obj) {
  if (typeof obj === "undefined") return "undefined";
  if (obj === null) return "null";
  return Object.prototype.toString.call(obj).match(/^\[object\s(.*)\]$/)[1];
}

function getAnyClass(obj) {
  if (typeof obj === "undefined") return "undefined";
  if (obj === null) return "null";
  return obj.constructor.name;
}

getClass("")   === "String";
getClass(true) === "Boolean";
getClass(0)    === "Number";
getClass([])   === "Array";
getClass({})   === "Object";
getClass(null) === "null";

getAnyClass(new (function Foo(){})) === "Foo";
getAnyClass(new class Foo{}) === "Foo";

// etc...