We will see how to Get Dropdown selected Value using javascript..?
First create javascript function as GetMaster1Details:
  1. function GetMaster1Details()
  2. {
  3. var value = document.getElementById("<%=ddlMaster1.ClientID%>");
  4. var getvalue = value.options[value.selectedIndex].value;
  5. var gettext = value.options[value.selectedIndex].text;
  6. alert("value:-" +" "+ getvalue + " "+ "Text:-" +" "+ gettext);
  7. }
Then use this function to dropdown on onchange event as:
  1. <asp:DropDownList ID="ddlMaster1" runat="server" onchange="GetMaster1Details()">
  2. </asp:DropDownList>
And See output is:
output