在asp.net中，使用asp.net Web控件和简单的HTML输入控件有何区别？

Question

In my asp.net web control form i am using two text box 1st is simple input html control and 2nd is asp.net input web control.

<form id="form1" runat="server">

        Email: <input type="text" id="txt_email" name="txt_email" value="" /><br />
        Email2: <asp:TextBox ID="txt_email2" runat="server"></asp:TextBox><br />       

        <asp:Button ID="btn_login" Name="btn_login" runat="server" Text="Button" 
            onclick="btn_login_Click" />

    </form>

I need to know what is the difference using simple control and asp.net input control both of them pass the value to code behind after the form submit. can any one help me on this?

Answer 1

As defined in your example input type="text" won't even be visible to code-behind because it is missing runat="server" attribute.

If you do add it - there're still differences. ASP.NET TextBox is more advanced and in par with the rest of ASP.NET model (eg it has property .Text vs. .Value of an HtmlInput control, it has events and other properties).

But if you simple need to pass text information back to the server, either of them will do the job.

Answer 2

The biggest differences are that

1. the asp.net controls are rendered on the server, and thus they have more overhead on your server than using traditional controls - traditional controls (by default) are rendered once then basically reside on the client's browser, asp controls are persistent on the server side.
2. the asp controls can be accessed and worked with directly in the code behind files.
3. asp controls have some additional tags that can be used on their fields usually.
4. as was pointed out by @Yuriy-Galanter, how the value is accessed is slightly different.

Answer 3

The asp:Textbox renders HTML to the client/browser when the page request is made. Picture the ASP.NET control, in this case an asp:TextBox as a server side bit of code that knows to render a <input type="text"> HTML element when the request for the aspx page is made to the server.

The ASP.NET compiler, when parsing your aspx page just spits out the <input type="text"> HTML element you have for Email: and for Email2: the ASP.NET compiler knows that is a server control because of the runat="server" tag. So the ASP.NET compiler, having a reference to the ASP.NET assemblies on the server, reads the code for the <asp:TextBox> and knows to ultimately respond to the page request with an <input type="text" id="txt_email2" />

The server side controls are accessible in your code behind page. So is accessible in the code behind but the <input> element is not. Good for you to consider in your research at this point, that if you add runat="server" to your element, it is accessible in your code behind.