How to Test a Web Application - How to review the HTML that’s sent to the browser
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To view the HTML for a page that’s displayed in a browser, you can use the Source command in your browser’s View menu. To illustrate, figure 2-19 presents the HTML that’s sent back to the browser after I selected a new value from the drop-down list, entered new values into the text boxes, and clicked the Calculate button. Although you’ll rarely need to view this code, it does give you a better idea of what’s going on behind the scenes.
First, you’ll see that this code doesn’t include any asp tags. That’s because these tags are rendered to standard HTML so the controls they represent can be displayed in the browser. For instance, the asp tag for the drop-down list in the first row of the table has been converted to an HTML select tag.
Second, you can see that the view state data is stored in a hidden input field named _VIEWSTATE. Here, the value of this field is encrypted so you can’t read it. Because the data in view state is passed to and from the browser automatically, you don’t have to handle the passing of this data in your code.
Third, you can see that the data that I selected from the drop-down list is included in the HTML. Although you can’t see it, the data that was entered into the text boxes is included as well. This illustrates that you don’t need view state to save the information that’s entered by the user. Instead, view state is used to maintain the state of properties that have been set by code. For example, it’s used to maintain the values that are loaded into the drop-down list the first time the user requests the form.
Keep in mind that this HTML is generated automatically by ASP.NET, so you don’t have to worry about it. You just develop the application by using Visual Studio in the way I’ve just described, and the rest of the work is done for you.
The HTML for the Future Value form after a post back
Description
To view the HTML for a page, use the View->Source command in the browser’s menu.
The HTML that the browser receives consists entirely of standard HTML tags because all of the ASP.NET tags are converted to standard HTML when the page is rendered.
View state data is stored in a hidden input field within the HTML. This data is encrypted so you can’t read it.
If the page contains validation controls and client scripting is enabled for those controls, the HTML for the page contains script to perform the validation on the client if the client supports DHTML.
Values that the user enters into a page are returned to the browser as part of the HTML for the page.
--------------------------------------------Figure 2-19 How to review the HTML that’s sent to the browser
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 This article is an excerpt from chapter two of Murach's ASP.NET 3.5 Web Programming with VB 2008, written by Anne Boehm (Murach, 2008; ISBN: 1890774472). Check it out today at your favorite bookstore. Buy this book now.
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