dltypeof - Custom JS typeof operator - DHTML Lab

JavaScript Programming: dltypeof() v1.0,
An Introduction

Using dltypeof()

Use dltypeof() whereever you would use typeof().

NOTE

The typeof() operator has two syntax variants:

typeof vExpression
typeof( vExpression )

The dltypeof() function has only one:

dltypeof( vExpression )

Don't forget the parentheses !

JS Objects

All the JS objects that are identified as "object" by typeof() are given more meaningful and obvious identifiers.

The JS Object object has a type of "jsobject" to clearly identify it as a JS object and to differentiate it from any other "object" that dltypeof() may fail to isolate as a unique type.

The JS Function.arguments object is given its own type of "arguments" since it is not a true array.

Any JS object that you create with a constructor function is identified with the name of the constructor function.
For example, let's say you create car objects with the following syntax:

function car( sMake, sModel, nWheels )
{
    this.sMake = sMake;
    this.sModel = sModel;
    this.nWheels = nWheels;
}

var oMerc = new car( "Mercedes", "Grand Sports Tourier", 4 );
var oToy  = new car( "Toyota", "Corolla", 4 );

Then:

dltypeof( oMerc ) returns "car"
dltypeof( oToy )  returns "car"

The following table lists all the possible return values for JS objects as well as the original typeof() return values

JS object	typeof() return value	dltypeof() return value

Boolean	boolean	boolean
Function	function	function
Number	number	number
String	string	string
[ no object ]	undefined	undefined

Arguments	object	arguments
Array	object	array
Date	object	date
Error	object	error
Math	object	math
Null	object	null
Object	object	jsobject
RegExp	object	regexp
[ custom ]	object	CustomConstructorFunctionName