createElement error. Custom DW Extention!

I am getting this error:

and here is my code, that i want to create select elements (option) by JavaScript. What code i use to create Select Options?

Just Console window saying that createElement is not JavaScript function.

function AddItem(selbox, Text, Value)
{
     // Create an Option object        
     var opt = document.createElement("option");

     // Add an Option object to Drop Down/List Box
     document.getElementById(selbox).options.add(opt);
     // Assign text and value to Option object
     opt.text = Text;
     opt.value = Value;

}

function load_str()
{
     var d = new Array();
     var d_v = new Array();
     
     d[0] = '0';
     d_v[0] = '0';
     d[1] = '1';
     d_v[1] = '1';
     d[2] = '2';
     d_v[2] = '2';
     d[3] = '3';
     d_v[3] = '3';
     d[4] = '4';
     d_v[4] = '4';
     d[5] = '5';
     d_v[5] = '5';
     
     var frm = document.scr;
     
     for (var i = 0; i < d.length; i++)
     {
          AddItem ('cboids', d, d_v)
     }
}

Any solutions to create Select options with JavaScript?