Using if/else by checking page URL
&lt;script language="JavaScript"&gt;


The script tag does not have a property language anymore, that property is deprecated. You should use the property type instead. Also the correct value for that property would be text/javascript.



&lt;!--


This is a relic from somewhere before all browsers could do JavaScript, please don't do it anymore.



function urlCheck() {


Nothing to say here. Except you should think about making it a habit to activate strict mode by default.



if(
window.location.href=="address to check"
)
{
/* some code to load */
}else{
document.write('&lt;div&gt;testing my super loaded div code sample&lt;/div&gt;')
}
}



Your indentation and use of whitespace is completely broken, fix it.
I've never seen a single if which was split over three lines, fix it.
You should not use == unless you know what it is doing. == performs casting as necessary to compare two values, while === compares their type and value.
I'm not a fan of creating HTML-elements in a string (document.createElement()), but for sure the opinions differ on this one vividly.




urlCheck() /* autoLoadFunction */


I suggest you either write your code directly and don't wrap it in a function (because that does nothing if you're going to directly run it after declaring) like this:

&lt;script type="text/javascript"&gt;
    if(window.location.href === "address to check") {
        // some code to load
    } else {
        document.write('&lt;div&gt;testing my super loaded div code sample&lt;/div&gt;')
    }
&lt;/script&gt;


Or run your code when the document is ready, by putting it at the end of the page (or use a framework which supports something like $(document).ready()):

&lt;script type="text/javascript"&gt;
    urlCheck();
&lt;/script&gt;




//--&gt;


As I already said, that's a relic, stop doing it.