Expression :<BR>
<TEXTAREA   Name=TextArea1   Rows=5   Cols=70   Wrap=On   >
x * x  +  y * y
</TEXTAREA><BR><BR>


Variables :<BR>
<TEXTAREA   Name=TextArea2   Rows=10   Cols=25   Wrap=Off   >
x = 3
y = 4
</TEXTAREA> &nbsp; &nbsp;


<INPUT   Type=BUTTON   Value="Evaluate"
   OnClick="EditResult.value=StrExpr_EvalVariablesThenExpr(TextArea1.value,TextArea2.value);"   > &nbsp; &nbsp;


Result : 
<INPUT   Type=TEXT   Name=EditResult   Size=25   Value=""   >



<SCRIPT>
/*
!------------------------------------------------------------------------------
! This program toolbox
!------------------------------------------------------------------------------
*/
/*
!---------------
! Evaluation routine
!---------------
! StrExpr_EvalVariablesThenExpr
!---------------
*/
//===== StrExpr_EvalVariablesThenExpr

function   StrExpr_EvalVariablesThenExpr   ( I_Expr , I_StrLines_VariableList )
{
   var  L_VariableList = new Array();
   var  L_i ;

   //----- Split variable list
   L_VariableList = I_StrLines_VariableList.split ( '\r\n' );

   //----- Evaluate variable list
   for ( L_i = 0 ; L_i < L_VariableList.length ; L_i++ )  {
      eval ( L_VariableList[L_i] );
   }

   //----- Evaluate main expression
   return  eval ( I_Expr );
}
</SCRIPT>