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wizard04 on 02/18/10

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Last Edited at 02/18/10 03:31pm

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JavaScript Type Tests

/ Published in: JavaScript

A more useful version of `typeof` and functions to test if a parameter is of a specified type.

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/****************************************
A more useful version of `typeof` and functions to test if a parameter is of a specified type.

Inspired by http://snipplr.com/view/1996/typeof--a-more-specific-typeof/

Examples:

var u;
is.Undefined(u)	//true
is.Number(u)	//false

var n=1;
is.Number(n)	//true; note that (n instanceof Number) would be false since n is a literal
is.Object(n)	//true
/****************************************/

//note that if argument `o` is an instance of more than one data type (which can happen if you mess with prototypes),
// only the first type tested will be returned
function typeOf(o)
{
	for(var type in is){ if(type != "Object" && is[type](o)) return type.toLowerCase(); }
	if(is.Object(o)) return "object";
	return "";
}

/*
//test all data types
//it's worth noting that, in IE, an HTML element is not considered an instance of Object
var u;
function f(){ this.toString=function(){return "[object f]"} };
var h = document.createElement("div");
var a = [u, null, true, (new Boolean), 1, (new Number), "s", (new String), /r/, (new RegExp), (new Date), [0,1], (new Array), 
	f, function(){}, (new Function), {}, (new Object), (new f), h];
for(var i=0; i<a.length; i++)
{
	console.log(a[i]+" : "+typeOf(a[i]));
}
*/

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