ASP.NET Server-side comments

Posted by nmarun on ASP.net Weblogs See other posts from ASP.net Weblogs or by nmarun
Published on Sat, 17 Apr 2010 00:22:15 GMT Indexed on 2010/04/17 0:23 UTC
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I believe a good number of you know about Server-side commenting. This blog is just like a revival to refresh your memories.

When you write comments in your .aspx/.ascx files, people usually write them as:

   1: <!-- This is a comment. -->

To show that it actually makes a difference for using the server-side commenting technique, I’ve started a web application project and my default.aspx page looks like this:

   1: <%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="ServerSideComment._Default" %>
   2: <asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
   3: </asp:Content>
   4: <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
   5:     <h2>
   6:         <!-- This is a comment -->
   7:         Welcome to ASP.NET!
   8:     </h2>
   9:     <p>
  10:         To learn more about ASP.NET visit <a href="http://www.asp.net" title="ASP.NET Website">www.asp.net</a>.
  11:     </p>
  12:     <p>
  13:         You can also find <a href="http://go.microsoft.com/fwlink/?LinkID=152368&amp;clcid=0x409"
  14:             title="MSDN ASP.NET Docs">documentation on ASP.NET at MSDN</a>.
  15:     </p>
  16: </asp:Content>

See the comment in line 6 and when I run the app, I can do a view source on the browser which shows up as:

   1: <h2>
   2:     <!-- This is a comment -->
   3:     Welcome to ASP.NET!
   4: </h2>

Using Fiddler shows the page size as:

screen

Let’s change the comment style and use server-side commenting technique.

   1: <h2>
   2:     <%-- This is a comment --%>
   3:     Welcome to ASP.NET!
   4: </h2>

Upon rendering, the view source looks like:

   1: <h2>
   2:     
   3:     Welcome to ASP.NET!
   4: </h2>

Fiddler now shows the page size as:

screen1

The difference is that client-side comments are ignored by the browser, but they are still sent down the pipe. With server-side comments, the compiler ignores everything inside this block.

Visual Studio’s Text Editor toolbar also puts comments as server-side ones. If you want to give it a shot, go to your design page and press Ctrl+K, Ctrl+C on some selected text and you’ll see it commented in the server-side commenting style.

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