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How to set programmatically a value of a watermarked TextBox via JavaScript - Update

, 22 Jan 2013
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How to programmatically set a value of a watermarked TextBox via JavaScript.

Some time ago I've published an article How to set programmatically a value of a watermarked TextBox via JavaScript about some specifics of working with a text input box decorated with a TextboxWatermark AJAX Extender control from the Ajax Control Toolkit library. The technique described in the article has proven useful for a number of developers so when the new release of the Ajax Control Toolkit has recently been announced I've decided to update the article to cover some of the braking changes in Ajax Control Toolkit components.

AJAX Control Toolkit changes

One of the most significant changes in the recent Ajax Control Toolkit release that affected everything is renaming namespaces and control names. Most of the JavaScript classes in the ACT has been moved into Sys.Extended.UI and some of them renamed.

Correspondingly the AjaxControlToolkitTextboxWrapper class that is crucial for the technique described in this article is now called Sys.Extended.UI.TextBoxWrapper and this is a breaking change. Most if its methods haven't been renamed and this is a good news however the new way of using the wrapper has been introduced.

Below are the code examples demonstrating how to write the code correctly with the new version of the ACT.

First we need to acquire an instance of the Sys.Extended.UI.TextBoxWrapper class for our textbox control and this is the newly introduced technique compared to the previous version of the ACT:

// get the instance of a textbox element
var textBox = $get(textBoxId);
// use the get_Wrapper static method of the TextBoxWrapper class to get the instance of the wrapper for the textbox
var wrapper = Sys.Extended.UI.TextBoxWrapper.get_Wrapper(textBox);

In the code above first I assume that the ACT is present so I don't have to check that Sys.Extended.UI namespace is defined. Secondly the code above is safe even if the textbox is not watermarked: the get_Wrapper static method will always return the instance of the TextBoxWrapper; the new instance will be created if the textbox is not watermarked.

Now we can set or get a value of the textbox using the instance of the TextBoxWrapper:

// get the textbox value
var oldValue = wrapper.get_Value();
// set the textbox value
wrapper.set_Value(newVlaue);

Conclusion

In a nutshell there are two major changes introduced in the new ACT release that affect the coding technique described here: the name of the textbox wrapper class has been changed; and now it's not required to check whether the textbox is watermarked to use the technique above.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Alexander Turlov
Architect
Canada Canada
Alexander Turlov has been working in IT industry since 1987. His programming experience includes such languages as FORTRAN, Pascal, and Basic, C, C++ and C#. He's been working for different industries like science, manufacturing, retail, utilities, finance, insurance, health care, education and so on. His area of interests is rich web applications development with .NET, C#, ASP.NET/MVC and JavaScript. He is working in software development doing architecture, design and development on .NET platform and using Microsoft Visual Studio, IIS and SQL Server as his primary tools, and a lot of other commercial and open source frameworks and tools. He holds a M.Sc. degree in physics and an MCSD.NET certification.

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