How to use JS API in Extension

I found this in another post and am able to get it to find the variables I need:

     
    var doc = Qv.GetCurrentDocument();
    var varsRetrieved = false;
    doc.SetOnUpdateComplete(function(){
        if(!varsRetrieved){
            Qv.GetDocument("").GetAllVariables(function(variables){
                var varlist = "";
                //Let pids = =concat(distinct [$(=$(%%v_SelectedKey($1)))], '$(%%v_SelValuesDelimiter)', [$(=$(%%v_SelectedKey($1)))]);
                for(var i = 0; i < variables.length; i++){
                    if (variables[i].name.indexOf("v_SelectedKeyValues") != -1) {
                        varlist += variables[i].name + " = " + variables[i].value + "\n";
                    }
                }
                alert(varlist);
                //alert("pids" + " = " + pids + "\n" + varlist);
            });
            varsRetrieved = true;
        }
    });

the problem that remains is that it doesn't give me a value, but an equation instead:

concat(distinct [$(=$(%%v_SelectedKey($1)))], '$(%%v_SelValuesDelimiter)', [$(=$(%%v_SelectedKey($1)))])

I need to know how to get the value of that equation in my extension script.

I made some progress on this by adding a text field to the definition likes this:

<Text Initial="" Expression="=$(%%v_SelectedKeyValues(1))"/>

Turns out the "variable" I was after is actually a function, and i need to pass in an index value as a parameter.

I was able to print the value using this line in my extension script:

this.Layout.Text0.text

While thats good progress and i'm learning, I still haven't solved my problem. I need to get the value of %%v_SelectedKeyValues(n) from my extension script.

Thanks for the help so far!