Javascript second-level linkage drop-down menu

< Html >
< Head >
< Title >
Test
</ Title >
< Script Language = " Javascript " >

// VaR select1_len = Document. frm. s1.options. length;
VaR select2 =   New Array ( 4 );


For (I = 0 ; I < 4 ; I ++ )
{
Select2 [I]= NewArray ();
}
// Define basic options
Select2 [ 0 ] [ 0 ] =   New Option ( " Select " , "   " );

Select2 [ 1 ] [ 0 ] =   New Option ( " PHP " , "   " );
Select2 [ 1 ] [ 1 ] =   New Option ( " ASP " , "   " );
Select2 [ 1 ] [ 2 ] =   New Option ( " JSP " , "   " );

Select2 [ 2 ] [ 0 ] =   New Option ( " C/C ++ " , "   " );
Select2 [ 2 ] [ 1 ] =   New Option ( " Java " , "   " );
Select2 [ 2 ] [ 2 ] =   New Option ( " C # " , "   " );

Select2 [ 3 ] [ 0 ] =   New Option ( " Perl " , "   " );
Select2 [ 3 ] [ 1 ] =   New Option ( " Ruby " , "   " );
Select2 [ 3 ] [ 2 ] =   New Option ( " Python " , "   " );


Function redirec (X)
{
VaR temp = Document. frm. S2;
  For (I = 0 ; I < Select2 [X]. length; I ++ )
  {
Temp. Options [I]=NewOption (select2 [x] [I]. Text, select2 [x] [I]. value );
}
Temp. Options [ 0 ]. Selected = True ;

}
</ Script >
</ Head >
< Body >
< Form name = " FRM " >
< Select name = " S1 " Onchange = " Redirec (this. Options. selectedindex) " >
  < Option selected > Select </ Option >
  < Option value = " 1 " > Script Language </ Option >
  < Option value = " 2 " > Advanced Language </ Option >
  < Option value = " 3 " > Other languages </ Option >
</ Select >
< Select name = " S2 " >
  < Option value = " Select " Selected > Select </ Option >
</ Select >
</ Form >
</ Body >
</ Html >