可以尝试以下代码-

Can you try the following code -

 <script language="javascript" type="text/javascript">
    function PopulateInventoryDropDown() {
        var InventoryDropDownID = event.srcElement.id.replace("InventoryTypeDDL", "InventoryDDL");
        // set the Inventory drop down list items here
    }
</script>

假设您已在模板字段中声明了DropDownLists，如下所示-

Assuming that you have declared DropDownLists inside template fields as below -

<asp:gridview id="GridView1" runat="server" autogeneratecolumns="False">
    <columns>
        <asp:templatefield>
            <itemtemplate>
                <asp:dropdownlist id="InventoryTypeDDL" onchange="PopulateInventoryDropDown();" runat="server">
                </asp:dropdownlist>
            </itemtemplate>
        </asp:templatefield>
        <asp:templatefield>
            <itemtemplate>
                <asp:dropdownlist id="InventoryDDL" runat="server">
                </asp:dropdownlist>
            </itemtemplate>
        </asp:templatefield>
    </columns>
</asp:gridview>