Why Tag Helpers in ASP.NET 5?

As ASP.NET 5 gets closer and closer to an official release date (in beta 7 at the time this post was written), the ASP.NET community is getting more curious (skeptical maybe?) about what is next.  While this is not a “Why ASP.NET 5?” post, it is in the spirit of providing evidence toward that objective – one way or another.  I find getting to know a specific feature that is new to a framework usually exposes underlying improvements to the overall story.  With that said, this is the first post in a series that will dive into tag helpers in ASP.NET 5.

First, I want to define what a tag helper is.  A tag helper is server-side code that allows for the customization of HTML markup (from the developers perspective) and manipulation of output rendered to the browser.  So, when an element is recognized in server-side processing as a tag helper, it is executed to generate HTML that will either enhance or even completely replace the original tag helper markup.   

For those who have been developing with ASP.NET MVC for awhile, tag helpers will supersede HTML helpers.  Many blog posts and articles I have read on the topic of tag helpers typically go into a detailed comparison of the advantages of the new improved syntax over HTML helpers.  While such a comparison is helpful to existing ASP.NET MVC developers, it could potentially confuse a new developer to ASP.NET as to the tag helper’s purpose or value.  So while I will offer a brief comparison a little later in this post, my angle will strive to be on the features as autonomously to HTML helpers as possible.

Now back to the main question at hand – why tag helpers in ASP.NET 5?  To put it simply, the purpose of a tag helper is ultimately bound to the pursuit of making code and markup easier to read and manage.

Let’s look at one example how.  This is the brief comparison I referenced earlier regarding HTML helpers.  In the code below, HTML helpers are defined to create an HTML form for submitting registration information:

For anyone brand new to ASP.NET, but strong in web development, the above code could look very confusing.  Questions might impede understanding like: What does that do?  Does it generate HTML?  How can I control it? …  I will not be answering those questions, since my focus is not to explain the HTML helper.  So let’s look at the same example, but with the syntax using tag helpers:

Consider how a polished web developer new to ASP.NET would read the markup above.  There would be no confusion over what the <form> or <div> tags were.  Instead, it would be apparent that some attributes in the elements are unique to ASP.NET, such as asp-controller.  With a little guess work, it could be inferred that a <form> tag will render to the browser with information on how and what to submit to.  It could also be guessed that the <div> tag is a placeholder for validation information.  Although the exact markup will not be the same as the tag helper, it certainly doesn’t look as foreign as HTML helpers.

How can you get started with tag helpers?  If you are using the default template for ASP.NET 5 with sample content in it, you are already using them!  The registration snippet referenced earlier is from that project.  However, if you start with an empty project, you will need to add support for tag helpers.  First, make sure you have referenced the package in the project.json file as seen here:

Next, to use the existing tag helpers, add the following to a view that uses it or at a global level such as in the _ViewImports.cshtml file:

Now you are ready to use the tag helpers provided with ASP.NET 5.  In an upcoming post, I will demonstrate how and why to develop your own custom tag helper!

    Copyright © Microsoft Corporation. All rights reserved.
    The code provided in this post is licensed under the Microsoft Public License (Ms-PL).

CSharp 6 in ASP.NET 5

Many of the new features of C# 6 aim to reduce the amount of code needed for common tasks.  ASP.NET 5 provides a lean, simplified approach to server-side coding for web sites and APIs. So working with ASP.NET 5 and C# 6 should prove the statement “less is more” to be true!

To showcase the new language features of C# 6, I want to do a simple comparison of how ‘it use to be done’ with ‘how it can be done now’.  To start, consider the following class that could be found in the Models folder in an ASP.NET MVC project:

With the new features of C# 6, you can accomplish the same with much less code, as seen here:

The above class is nearly half the lines of the previous definition, yet accomplishes the same exact objective.  Let’s look at how this was accomplished.

Both classes declared three properties, FirstName, LastName, and FullName.  The first and last name properties are read/write and have a business rule of being initialized to a default value, while the remaining property is read-only.  In the ‘before’ approach, this is how the properties were defined:

Now this can be greatly simplified with new features such as auto property initializers and read-only properties with expression bodies as seen here:

After the FullName you will notice the => syntax which indicates the property will contain an expression body.  The expression in this example is a string concatenation of the first name and last name, which is also simplified with the use of string interpolation.  The $”{s1} {s2}” syntax is much easier to read and manage than the String.Format method approach.

Methods can also contain expression bodies, as seen in the GetLastNameFirst method defined here:

Another feature that can help reduce code a little is the use of using static syntax. Consider the final method of the class:

In the code above, instead of typing String.Concat, I could just type Concat. This is possible because of the using static System.String statement.  This allows calls on all static members of the class without typing the class name first.  Depending on how this gets used, this will either simplify or complicate how your code reads, so use with discretion!

The following code is a controller that creates an instance of both classes in order to test the data values:

Compare line 8 with line 12. Notice the nameof keyword? It provides the simple service of returning the name of the variable it references as a string. Very handy for logging and testing!

If you would like to experiment with the language features, check out the interactive C# 6 demo which contains code very similar to what was shown in this post.  If you would like to examine the code in ASP.NET 5, you can view or download it at

    Copyright © Microsoft Corporation. All rights reserved.
    The code provided in this post is licensed under the Microsoft Public License (Ms-PL).

Building Windows Apps with JavaScript Is Even Easier

Building Windows applications using JavaScript on Windows 10 is opening up new opportunities for developers. We cover how you can leverage your current web workflow for publishing code on the server while still having a single application published in the Windows store. This session covers the investments we’ve made for hosted content on the web including updates to the WebView control.
    Copyright © Microsoft Corporation. All rights reserved.
    The code provided in this post is licensed under the Microsoft Public License (Ms-PL).

C# 6 Features in Action!

With Visual Studio 2015 available for all, I wanted to explore new language features in C# 6 that you can try right from this blog post!

Interactive Code Sample

// allows calling static members without class name
using static System.Console;
using static System.String;
using static System.Linq.Enumerable;

public class Person
    // auto property initializer
    public string FirstName { get; set; } = "John";
    public string LastName { get; set; } = "Doe";

    // readonly property initialized with expression body
    // assigned to value returned from string interpolation 
    public string FullName => $"{FirstName} {LastName}";

    // method defined with expression body
    public string GetLastNameFirst() => $"{LastName.ToUpper()}, {FirstName}";

    public void Test(string testName)
        var dash = "-";
        var dashLength = 30 - testName.Length;
        // use {{ and }} for literal "{" and "}"
        // use {{{ and }}} to wrap a value within "{" and "}" 
        // repeating a dash with length not to exceed 30
        // WriteLine | Concat | Repeat == using static :) 
        WriteLine($"{{{testName}}} {Concat(Repeat(dash,dashLength))}");

// test default
var um = new Person();
// nameof returns the string name of the instance

// test initialized
var palermo4 = new Person() 
   { FirstName = "Michael", LastName = "Palermo" };

// interactive!  click go -->
    Copyright © Microsoft Corporation. All rights reserved.
    The code provided in this post is licensed under the Microsoft Public License (Ms-PL).

10 Common Mistakes Web Developers Make

web developer making a mistakeThere seems to be endless choices regarding how to accomplish the same task - to develop a website that works in today's modern web. Web developers have to choose a web hosting platform and underlying data storage, which tools to write HTML, CSS, and JavaScript in, how design will be implemented, and what potential JavaScript libraries/frameworks to include. Once choices are narrowed down, the online world is filled with articles, forums, and samples that provide tips for making a better web experience. Yet no matter which path is taken, all developers are susceptible to mistakes. Although some mistakes will be related to a specific approach, there are challenges shared among all web developers. So through research, experience, and recent observations, I thought I would share a list I compiled of ten common mistakes I see web developers make - and how to avoid them.

The following list is in no particular order.

1)  Writing old school HTML

Mistake: The early days of the internet had much less options for markup than we do today. However, old habits die hard, and many still write their HTML as if we were still in the 20th century. Examples here are using <table> elements for layout , <span> or <div> elements when other semantic-specific tags would be more appropriate, or using tags that are not supported in current HTML standard such as <center> or <font>, or spacing items on a page with a large number of &nbsp; entities.

Impact: Writing last decade's HTML can result in over complicated markup that will behave inconsistently across multiple browsers.

How to avoid: Stop using <table> element for layout of content, and limit usage for it to displaying tabular data. Get acquainted with the current markup options available such as seen at Use HTML to describe what the content is, not how it will be displayed. To display your content correctly, use CSS (

2 )  "It works in my browser…"

Mistake: A developer may be fond of a particular browser or really despise one, and might primarily test web pages with that bias in view. It is also possible that code samples found online may be written without factoring how it would render in other browsers. Also, some browsers have different default values for styles.

Impact: Writing a browser-centric site will likely result in very poor quality when displayed in other browsers.

How to avoid: It would not be practical to test web pages in every browser & version during development. However, having a regular interval of checking how your site will appear in multiple browsers is a good approach. Sites such as show snapshots of how a given page would render over multiple browsers/versions/platforms. Tools such as Visual Studio ( can also invoke multiple browsers to display a single page you are working on. When designing with CSS, consider "resetting" all the defaults as shown at

If your site is using any CSS features created specific for a browser, be cautious as to how you will approach vendor prefixes such as -webkit-, -moz-, or -ms-.  For guidance on industry trends in this regard, it would be worth your time to examine the following references:

While the above references explain a movement away from vendor prefixes and why, this site provides practical suggestions on how to work through this today.

3)  Bad form

Mistake: Prompting a user to provide any information (especially when entered into a text field) and assuming the data will be received as intended.

Impact: Many things can (and likely will) go wrong when user entry is trusted. Pages may fail if required data is not provided, or data received is not compatible with an underlying data scheme. Even more serious is the intentional violation of the site's database, perhaps through Injection attacks (see

How to avoid: The first bit of advice here is to make sure it is clear to the user what type of data you are looking for. These days, asking for an address could result in either a business, home, or even email address! In addition to be specific, take advantage of data validation techniques available in today's HTML as seen at this article No matter how data is validated on the browser side, be sure it is always validated on the server-side as well. Never allow a concatenated T-SQL statement to use data from user entry without confirmation the each field is the type of data it should be.

4)  Bloated responses

Mistake: The page is filled with many high quality graphics and/or pictures, scaled down with use of <img> element height and width attributes. Files linked from the page such as CSS and JavaScript are large. The source HTML markup may also be unnecessarily complex and extensive.

Impact: The time to have a page completely render becomes long enough for some users to give up or even impatiently re-request the whole page again. In some cases, errors will occur if page processing is waiting too long.

How to avoid: Don't adopt the mindset that access to the internet is getting faster and faster - thus allowing for bloated scenarios. Instead, consider everything going back and forth from the browser to your site as a cost. A major offender in page bloat is images.  To minimize the cost of images that slow down page loads, try these three tips:

  1. Ask yourself: "Are all my graphics absolutely necessary?" If not, remove unneeded images.
  2. Minimize the file size of your images with tools such as Shrink O'Matic or RIOT
  3. Preload images. This will not improve the cost on initial download, but can make other pages on site that use the images load much faster. For tips on this, see

Another way to reduce cost is to minify linked CSS and JavaScript files. There are plenty of tools out there to assist in this endeavor such as Minify CSS and Minify JS

Before we leave this topic, strive to be current with HTML (see mistake #1) and use good judgment when using <style> or <script> tags in HTML.

5)  Creating code that *should* work

Mistake: Whether it is JavaScript or code running on the server, a developer has tested and confirmed that it works, thereby concluding it should still work once deployed. The code executes without error trapping, because it worked when it was tested by developer.

Impact: Sites without proper error checking may reveal the errors to the end users in an ugly way. Not only can the user experience be dramatically impacted, the type of error message content could provide clues to a hacker as to how to infiltrate a site.

How to avoid: To err is human, so bring that philosophy to coding. With JavaScript, be sure to implement good techniques to prevent errors as well as catch them. Although this article addresses JavaScript coding for Windows Apps, the majority of the topics apply to web development too, and it is full of good tips! Another aid to help create solid code that can hold up well to future changes in code is unit testing (see

Failures in server-side code should be caught without the user seeing any of the nerdy details. Reveal only what is necessary, and be sure to set up friendly error pages for things like HTTP 404s (see

6)  Writing forking code

Mistake: With the noble notion of supporting all browsers and versions, a developer creates code to respond to each possible scenario. The code becomes a heap of if statements, forking in all sorts of direction.

Impact: As new versions of browsers update, management of code files become bulky and difficult to manage.

How to avoid: Implement feature detection in code versus browser/version detection. Feature detection techniques not only dramatically reduce the amount of code, it is much easier to read and manage. Consider using a library such as Modernizr ( which not only helps with feature detection, it also automatically helps provide fallback support for older browsers not up to speed with HTML5 or CSS3.

7)  Designing unresponsively

Mistake: Site development assumes viewing in the same size monitor as the developer/designer.

Impact: When viewing the site in mobile devices or very large screens, the user experience suffers with either not being able to see important aspects of the page or even preventing navigation to other pages.

How to avoid: Think responsively. Use responsive design (see in your sites. A very popular library ready to serve in this area is Bootstrap (

8)  Making meaningless pages

Mistake: Producing public facing pages with content that might be very useful, but not providing any hints to search engines. Accessibility features are not implemented.

Impact: Pages are not as discoverable through search engines and therefore may receive little or no visits. The page content may be very cryptic to users with impaired vision.

How to avoid: Use SEO (search engine optimizations) and support accessibility in HTML. Regarding SEO, be sure to add <meta> tags to provide meaning to a page with keywords and description. A good write up on that is found at To enable a better accessibility experience, be determined to provide an alt="your image description" attribute in each of your <img> or <area> tags. Of course, there is more to do and further suggestions can be investigated at You can also test a public web page at to see if it is compliant with Section 508 (

9)  Producing sites that are too refreshing

Mistake: Creating a site that requires full refreshes of a page for each interaction.

Impact: Similar to bloated pages (see mistake #4), performance of page loading time is affected. The user experience lacks fluidity, and each interaction could cause a brief (or long) resetting of the page.

How to avoid: One quick way to avoid this is by determining if posting back to the server is truly required. For example, client-side script can be used to provide immediate results when there is no dependency for server-side resources. You can also embrace AJAX techniques (see or go further with a single-page application “SPA” (see approach. Popular JavaScript libraries/frameworks are available to make adoption of these methods much easier, such as,, and

10)  Working too much

Mistake: A developer spends a long time creating web content. Time might be spent doing repetitive tasks, or simply typing a lot.

Impact: Time for initial web site launch or subsequent updates is too lengthy. Value of the developer diminishes when it appears other developers are doing comparable work in less time and with less effort. Manual labor is prone to mistakes, and troubleshooting mistakes takes even more time.

How to avoid: Explore your options. Consider using new tools or new process techniques for every stage of development. For example, how does your current code editor compare to Sublime Text ( or Visual Studio ( Regardless of what code editor you are using, have you recently dived into its features? Perhaps a small investment of your time perusing the documentation could unveil a new way to do something that could save hours & hours of time later. For example, note how an extension to Visual Studio can increase productivity for web developers as seen in this post

Don't miss out on tools available on the web to help! For example, check out the tools at to simplify testing (across multiple platforms and devices) and troubleshooting.

You can also help reduce time and mistakes by automating processes. An example of this is using a tool like Grunt ( that can automate things such as the minifying of files (see mistake #4). Another example is Bower ( which can help manage libraries/frameworks (see mistake #9).

How about the web server itself? With the help of services such as Microsoft Azure Web Apps (, you can quickly create a site for virtually any development scenario that can easily scale with your business!


By identifying common mistakes, web developers can eliminate much frustration that others have already endured. Not only is it important to acknowledge, but when we understand the impact of a mistake and take measures to avoid it, we can create a development process catered to our preferences – and do so with confidence!

    Copyright © Microsoft Corporation. All rights reserved.
    The code provided in this post is licensed under the Microsoft Public License (Ms-PL).
    Copyright © Microsoft Corporation. All rights reserved.
    The code provided in this post is licensed under the Microsoft Public License (Ms-PL).

Windows 10 Background Execution and Multitasking

The Universal Windows Platform introduces new mechanisms to allow applications to run while not in the foreground. As well as Background Tasks and Triggers, UWP adds the ability for applications to extended their execution time in the background. Learn how to use these new features and how new resource policies affect how and when your application runs in the background.
    Copyright © Microsoft Corporation. All rights reserved.
    The code provided in this post is licensed under the Microsoft Public License (Ms-PL).

Reveal Hidden Content Using Hash in URL

Suppose you have a web page that provides details on a given product.  The page has preloaded a number of products in HTML, but they are hidden from viewing via jQuery hide method.  If a user clicks a product link on the page, then the jQuery show method explicitly reveals it.  Now the user visits the page from another with a hash in URL like and the desired result is to automatically reveal the details for that product?  That was a question posed recently at StackOverflow, and this is how I answered it:

The key line of code above is line 11 of jqueryHash snippet. If the URL ended with #shoes, the details for that product would be automatically revealed. Note the code snippet does not do any validation of the hash (for brevity).

There were a number of answers given at the StackOverflow post, each with merit.  You can test my answer at my codepen testing grounds.

    Copyright © Microsoft Corporation. All rights reserved.
    The code provided in this post is licensed under the Microsoft Public License (Ms-PL).

WebCamp MVC Events

imageI have been inspired to write some blog posts that feature highlights from a series of WebCamps I delivered along the west coast.  In this post, I am going to share a discovery I made when observing traditional ASP.NET (Web Form) developers attempt the switch to ASP.NET MVC.

The first question that might come to mind is: Why leave Web Forms?  The real answer is – you don’t have to.  However, here are a few reasons why many may choose to do so in the near future:

  • Web Forms are phat! …yet fat.  The page source is typically bloated with view state info.
  • Web Forms don’t encourage separation of concerns as does MVC.
  • Web Forms request/response model invokes many events and is process intensive.
  • Web Forms do not exist in ASP.NET 5.

The latter reason was the primary motivator for WebCamp attendees to consider moving to MVC because it exists prominently in ASP.NET 5 (by the way, Web Pages do too!)

You can learn a lot about what is on an attendee’s mind by a question he/she asked.  The following question is a classic example – and served as inspiration for this blog post and title:

“How do I respond to the click event of a button?”

The concept of interacting with elements on a page via event handlers is an easy concept to learn.  Unlearning it (for some) is a struggle.  MVC doesn’t use events like Web Forms do.  Instead of simply stating it doesn’t do that, I wanted to show how it was accomplished in MVC.  I used a very simple scenario -  one submit button on a page that displays a message when clicked.  Here is a snippet from the view:

<h2>Button Click Event in MVC</h2>
@using (Html.BeginForm())
    <input type="submit" name="submit" value="Submit" />    

And here is the code in the controller:

Palermo4Mvc.Controllers { public class DemoController : Controller { // GET: Demo public ActionResult Index() { return View(); } [HttpPost] public ActionResult Index(string submit) { ViewBag.Message = "Muhahaha!"; return View(); } } }

I went through the process of explaining how requests hit controllers first, then views were rendered.  Now that a simple task was accomplished, there was the inevitable questions that follow such as ‘What if I have two buttons?  How do I retrieve submitted values in the controller?  Do I still have access to querystring data? …’

What became clearer to me each time I presented a WebCamp is the need to bridge a gap starting with a simple process they already knew well.  Once the concept came into view (no pun) the attendees would organically accelerate their own learning path  Many new MVC developers have arisen from these events, and I was honored to be a part of that process!

    Copyright © Microsoft Corporation. All rights reserved.
    The code provided in this post is licensed under the Microsoft Public License (Ms-PL).

WebCamp Essentials

imageSince the beginning of this year, I have had the privilege to tour across the west coast speaking at WebCamps featuring content and demos using Visual Studio 2013.  A common theme across all of these camps was the positive reaction to some particular demos targeting the productive features enhancing web development.  Specifically, these demos were showcasing the goodness found in the Web Essentials extension for Visual Studio.  Although I have been a fan for years, it was surprising to me how many long-time ASP.NET developers were not using it or even aware of it.  Thus I am inspired to spread the word about this free add-in which is available for multiple versions of Visual Studio.  It was truly an essential part of the WebCamp experience, thus why I named this post “WebCamp Essentials”.

In the spirit of the WebCamps, I would like to reveal the features that seemed to render the highest level of praise or interest – and in no particular order.  Although all the features are listed categorically on the Web Essentials home page, I wanted to iterate the camp favorites by listing them under problems they address.

“What file is this static content in?”

When testing your site in a browser, you may want to know where (source file) a visual element is coming from.  Since sites can be complex with nested content, it may not be easily discernable what file a static element resides in.  With the browser link feature, you can toggle a mode in the browser that will enable visual selection of an element which will reveal in Visual Studio the source file in which it resides.  Not only can you find content, you can change it right in the browser and see how it updates your file in Visual Studio automagically!   This is made possible by script injected into the page when launching from Visual Studio – and it works across all the modern browsers.

“I prefer less typing!”

With minimal typing, you can create HTML content quickly with Zen Coding.  A simple example:

<!-- type this and then tab -->

<!-- becomes -->
<div id="demo" class="groovy">Amet, consectetur adipiscing elit.</div>


“Collapsible regions please!”

A popular feature in the C# world, this extension makes it possible to do the same in HTML, JavaScript, or CSS.  Content inside the region can be collapsed visibly to help organize. 


<!--#region name-->



//#region name



/*#region name */

/*#endregion */

As mentioned, these are just a few of the many features provided with Web Essentials.  If you are a web developer using Visual Studio – it is simply essential for you to employ it!

    Copyright © Microsoft Corporation. All rights reserved.
    The code provided in this post is licensed under the Microsoft Public License (Ms-PL).