Technical interview questions and answers are critical when preparing for an AJAX Interview because companies want to evaluate your understanding of asynchronous communication, XMLHttpRequest, JSON handling, DOM manipulation, and interactive web applications. AJAX is considered a core concept in modern web development, and many companies include it as part of their technical rounds for frontend and full-stack developer roles. Organizations like TCS, Infosys, Wipro, Cognizant, and Capgemini frequently ask AJAX-related questions to check whether candidates can build dynamic, responsive, and efficient web pages. This guide includes commonly asked AJAX interview questions with clear explanations to help freshers and job seekers strengthen their web development fundamentals. These questions will improve your preparation for placement interviews, coding rounds, and real-time project discussions.
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131. What is the difference between an interface and abstract class?
In the interface all methods must be abstract; in the abstract class some methods can be concrete. In the interface no accessibility modifiers are allowed, which is ok in abstract classes.
132. What is an abstract class?
A class that cannot be instantiated. A concept in C++ known as pure virtual method. A class that must be inherited and have the methods over-ridden. Essentially, it is a blueprint for a class without any implementation.
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133. Does C# support multiple-inheritance?
No.
134. Who is a protected class-level variable available to?
It is available to any sub-class (a class inheriting this class).
135. Whats the top .NET class that everything is derived from?
System.Object.
136. What does the term immutable mean?
The data value may not be changed. Note: The variable value may be changed, but the original immutable data value was discarded and a new data value was created in memory.
137. whats the difference between System.String and System.Text.StringBuilder classes?
System.String is immutable. System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed.
138. whats the advantage of using System.Text.StringBuilder over System.String?
StringBuilder is more efficient in cases where there is a large amount of string manipulation. Strings are immutable, so each time a string is changed, a new instance in memory is created.
139. Whats the difference between the System.Array.CopyTo() and System.Array.Clone()?
The first one performs a deep copy of the array, the second one is shallow. A shallow copy of an Array copies only the elements of the Array, whether they are reference types or value types, but it does not copy the objects that the references refer to. The references in the new Array point to the same objects that the references in the original Array point to. In contrast, a deep copy of an Array copies the elements and everything directly or indirectly referenced by the elements.
140. Whats the .NET collection class that allows an element to be accessed using a unique key?