Passing Javascript variable to <a href >

Alternatively you could just use a document.write:

<script type="text\javascript">
var loc = "http://";
document.write('<a href="' + loc + '">Link text</a>');
</script>

put id attribute on anchor element

<a id="link2">

set href attribute on page load event:

(function() {
    var scrt_var = 10;
    var strLink = "2.html&Key=" + scrt_var;
    document.getElementById("link2").setAttribute("href",strLink);
})();

If you want it to be dynamic, so that the value of the variable at the time of the click is used, do the following:

<script language="javascript" type="text/javascript">
var scrt_var = 10; 
</script>
<a href="2.html" onclick="location.href=this.href+'?key='+scrt_var;return false;">Link</a>

Of course, that's the quick and dirty solution. You should really have a script that after DOM load adds an onclick handler to all relevant <a> elements.