Javascript for dynamic url content

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HTML

<a class="dyna" href="[DYN]/usr/page.aspx?pgid=1">www.example.com</a><br/>
<a class="dyna" href="[DYN]/usr/page.aspx?pgid=1">www.site.com</a><br/>
<a class="dyna" href="[DYN]/usr/page.aspx?pgid=1">www.bla.com</a><br/>

JS

var l = document.getElementsByClassName("dyna").length;

for (var i=0; l > 0; l--){
    var inner = document.getElementsByClassName("dyna")[i].innerHTML,
        x = document.getElementsByClassName("dyna")[i].getAttribute('href'),
        y = x.replace('[DYN]','http://'+inner);

    document.getElementsByClassName("dyna")[i].setAttribute('href',y);

    i++
}

Note: I used a class to retrieve the anchors but you can look for TagName a if you prefer ...

Using javascript get domainname and add it to create link you need.

var domain = document.domain;
var link = '<a href=\"'+domain+'/usr/page.aspx?pgid=1\">www.example.com</a>';
link // here you get a anchor tag html.

To get the domain name example.com from the set of possible subdomains sub1.example.com sub2.example.com sub3.example.com. you can try below code.

var parts = location.hostname.split('.');
var subDomain = parts.shift();
var upperLevelDomain = parts.join('.');

To get only the second-level-domain, you might use

var secondLevelDomain = parts.slice(-2).join('.');

The href attribute can be a relative¹ path:

<a href="/path/to/page">Blah</a>

The link would grab the current protocol, host, and port and append whatever comes next.

Sample scenario: let's pretend the current URL is http://yoursite.com/pages/links.html the above example anchor would navigate when clicked to http://yoursite.com/path/to/page.

NOTE: If you omit the leading slash in the relative path

<a href="path/to/page">Blah</a>

The current full path will be used.

Sample scenario: let's pretende the current URL is http://yoursite.com/pages/links.html then the anchor without leading slash would navigate when clicked to http://yoursite.com/pages/path/to/page

¹: relative as in relative to the current page