The target id below is map_external, but I would like to get map_external(and a number)

I have this:

$('#jqt').bind('pageAnimationStart', function(e, info){
           if (e.target.id == 'map_external') {
                 if (info.direction =='in') {
                    localiser();
                }

and it works, and my target page looks like this:

<div id="map_external">
content....
</div>

but I would like to have a random number aswell, like this:

<div id="map_external<%=asp random number%>">
content....
</div>

so how do i write if (e.target.id == 'map_external') so that it gets map_external and a number(any number)? Thanks!