Concatenate Dynamic Variable Names

I have a table that I populate with an array using ASP. As each row is created, the form object names are appended a numeric, such as:

i = 1
<select name="select<%=i%>">
...
...
...
i = i+1
next

I then pass "i" to a javascript function, so that I can access the values of each form object. I can't figure out how to properly concatenate the "i" and still allow access to the value in the form object. Currently I have:

var ps = 'platSymbol' + I;
alert(ps)
var sel = 'document.frmUpdPlatGrp.' + ps + '.value'
alert(sel)

I know I'm wrong, as this comes back as a complete string. Ultimately I want to have something like this:

var s = document.frmUpdPlatGrp.platSymbol2.value - so that I can actually get the value.