Easier Type Handling

a common task when writing multi-use functions, is deciphering the type of data passed to the function.

Javascript's built-in data identification methods complicate function writing, by imposing a "20 questions" style interogation to determine the actual, useful to a programmer, type.

they also slow down functions, requiring both a function execution and a comparision operation upon every type guess.

a common method is something like:
if(typeof x=='string'){ };

but this has several limitations. for example:
x=[1,2,3];
typeof x; //returns 'object'

safely catching an undefined is often done like:
if(typeof x != 'undefined' ){ };

my function making got a lot easier after writing these simple prototypes:

String.prototype.type="string";
Array.prototype.type="array";
Number.prototype.type="number";
Boolean.prototype.type="boolean";
Date.prototype.type="date";
Object.prototype.type="object";
RegExp.prototype.type="regexp";
Function.prototype.type="function"
if(!!window.XML)XML.prototype.type="xml";

String.prototype.isString=1;
Array.prototype.isArray=1;
Number.prototype.isNumber=1;
Boolean.prototype.isBoolean=1;
Date.prototype.isDate=1;
Object.prototype.isObject=1;
RegExp.prototype.isRegExp=1;
Function.prototype.isFunction=1;
if(!!window.XML)XML.prototype.isXML=1;

the result?

shorter simpler code.

examples:

// smarter object typin':
[1,2,3].type; //returns 'array'


//when expecting a string or array possibility:
y=x.isString?x:x.join();

//more-flexible event handling:

function doBold(elm){ //accepts element object or id string...
if(elm.isString){elm=document.getElementById(elm);}
elm.style.fontWeight="bold";
}//end doBold


// detect an undefined variable:
if( ! x.type){ alert('x is undefined')};



by tucking the protos in your script file, you get simpler, faster-executing code. (for a tiny bit of overhead)

if script length is of upmost concern (as in a bookmarklet), these smaller protos give you simpler typing: (without the speed benefits...)

Object.prototype.type=function(){return typeof this;};
//usage:
switch(x.type()){
case 'string': return x;
case 'date': return x.toLocaleString();
case 'array': return x.join('
');
default: return x.toString();
}//end switch;

//another one:
Object.prototype.isType=function(strType){return (!! typeof this === strType)};
//usage:
x=101;
x.isType('string'); //returns false
x.isType('number'); //returns true