Step towards SharePoint

 I just added some basic components like  TextBox ,  RequiredfieldValidator , and validation summary controls only. Its shows the following error Adding the following element in  web.config   <appSettings> <add key = "ValidationSettings:UnobtrusiveValidationMode" value = "None" /> </appSettings>

http://msdn.microsoft.com/en-us/library/office/dn268594(v=office.15).aspx

EnabledScript = " javascript:var EnableDisable=function(){             this.clientContext=SP.ClientContext.get_current();             this.selectedItems=SP.ListOperation.Selection.getSelectedItems(this.clientContext);             var ci = CountDictionary(selectedItems);             return (ci == 1);             };EnableDisable(); " Hope this will helps you............

I was struggling to get my custom images loaded for use on my custom ribbon action that I defined in my SharePoint Hosted App for SharePoint 2013. so, you could use name of the application instead of ~appWebUrl

Encapsulation provides the explicit boundary between an object's abstract interface (its abstraction) and its internal implementation details. Encapsulation puts the implementation details "in a capsule." Encapsulation tells users which features are stable, permanent services of the object and which features are implementation details that are subject to change without notice. Encapsulation helps the developers of an abstraction: it provides the freedom to implement the abstraction in any way consistent with the interface. (Encapsulation tells developers exactly what users can and cannot access.) Encapsulation also helps the users of an abstraction: it provides protection by preventing dependence on volatile implementation details. Abstraction provides business value; encapsulation "protects" these abstractions. If a developer provides a good abstraction, users won't be tempted to peek at the object's internal mechanisms. Encapsulation is simply a safet...

People Editor control is not working properly inside the Update Panel Soln: Just include the  entityeditor.js  file explicitly on the page < script type ="text/javascript" src ="/_layouts/15/entityeditor.js"></ script >

Problem Suspect that because date time control is located under update panel, and page didn’t manage to load in picker’s javascript. Solution <script type = "text/javascript" src = "/_layouts/datepicker.js" ></script> Just include the datepicker.js file explicitly on the page More :  Problems with UpdatePanel on SharePoint