javascript reflection in jQuery

String: typeof object === "string"
Number: typeof object === "number"
Boolean: typeof object === "boolean"
Object: typeof object === "object"
Function: jQuery.isFunction(object)
Array: jQuery.isArray(object)
Element: object.nodeType
null: object === null
undefined: typeof variable === "undefined" or object.prop === undefined
null or undefined: object == null

it must be "new"ed.

The following is constructor which prevent not using "new" keyword

javascript scope

In JavaScript, {blocks} do not have scope.

object literal

var myObject = { name: "Jack B. Nimble", 'goto': 'Jail', grade: 'A', level: 3, "3": "three" };
alert(myObject.name);
alert(myObject["name"]);
alert(myObject["goto"]);
alert(myObject.goto); //ok
alert(myObject["3"]);
//alert(myObject.3); //error

function overload

function.length can tell you the number of parameters defined, using this we can create overload functions