type() - a better typeof

README.md

type.js - offers an more consistent type checking of native values. It relays on the [[Class]] of objects instead on typeof results.

type2.js - variation that returns "object" for wrapped natives. This one is probably more noob-immune, avoiding some possible strange situations.

Consider something like this:

// Defined by third...
var foo = new String("foo");

// ...

function noob( str ) {
    if ( type(str) !== "string" ) {
        throw new TypeError("string expected");
    }

    return ( str === "foo" );
}

If the type check returns "string", then noob will return false because of the strict equality check ===. To avoid similar situations, "object" is returned for wrapped strings, numbers and booleans.

type.js

(function($){

	var toString = Object.prototype.toString,
		classes = "Boolean Number String Function Array Date RegExp Object".split(" "),
		class2type = {};
		
	for ( var i = 0; i < classes.length; ++i ) {
		class2type[ "[object " + classes[i] + "]" ] = classes[i].toLowerCase();
	}
	
	$.type = function( obj ) {
		return obj == null ?
			"" + obj :
			class2type[ toString.call( obj ) ] || "object";
	};
	
})(this.jQuery || this);

type2.js

(function($){

	var map = {},
		toStr = map.toString,
		names = "boolean number string Function Array Date RegExp".split(" ");
		
	for ( var i = 0; i < names.length; ++i ) {
		map[ names[i].replace(/^([A-Z]\w+)/, "[object $1]") ] = names[i].toLowerCase();
	}
	
	$.type = function( obj ) {
		return obj == null && ( "" + obj )
			|| map[ typeof obj ]
			|| map[ toStr.call( obj ) ]
			|| "object";
	};
	
})(this.jQuery || this);

There are inconsistencies even between specs (that is reasonable), I know.