Object.prototype.constructor

var o = {};
o.constructor === Object; // true

var a = [];
a.constructor === Array; // true

var n = new Number(3);
n.constructor === Number; // true

function Tree(name) {
  this.name = name;
}

var theTree = new Tree(" ");
console.log("theTree.constructor  " + theTree.constructor);

theTree.constructor  function Tree(name) {
  this.name = name;
}

function Type() {}

var types = [
  new Array(),
  [],
  new Boolean(),
  true, //  
  new Date(),
  new Error(),
  new Function(),
  function () {},
  Math,
  new Number(),
  1, //  
  new Object(),
  {},
  new RegExp(),
  /(?:)/,
  new String(),
  "", //  
];

for (var i = 0; i < types.length; i++) {
  types[i].constructor = Type;
  types[i] = [
    types[i].constructor,
    types[i] instanceof Type,
    types[i].toString(),
  ];
}

console.log(types.join("\n"));

function Type() {},false,
function Type() {},false,
function Type() {},false,false
function Boolean() {
    [native code]
},false,true
function Type() {},false,Mon Sep 01 2014 16:03:49 GMT+0600
function Type() {},false,Error
function Type() {},false,function anonymous() {

}
function Type() {},false,function () {}
function Type() {},false,[object Math]
function Type() {},false,0
function Number() {
    [native code]
},false,1
function Type() {},false,[object Object]
function Type() {},false,[object Object]
function Type() {},false,/(?:)/
function Type() {},false,/(?:)/
function Type() {},false,
function String() {
    [native code]
},false,