ExtJS Sencha Interview Question and Answer

Q1. What is ExtJS Sencha?

Answer: ExtJS Sencha is a JavaScript framework used for building feature-rich and interactive web applications.

Q2. What is the Model-View-Controller (MVC) architecture in ExtJS Sencha?

Answer: The MVC architecture in ExtJS Sencha separates an application into three distinct components: Model, View, and Controller. Models represent the data, Views handle the user interface, and Controllers manage the application logic.

Q3. How do you create a new ExtJS Sencha application?

Answer: To create a new ExtJS Sencha application, you can use the Sencha Cmd tool and run the command "sencha generate app [appName] [appPath]".

Q4. What are the key components in ExtJS Sencha?

Answer: ExtJS Sencha provides various components, including grids, forms, charts, trees, panels, and buttons, to build the user interface of a web application.

Q5. How can you handle events in ExtJS Sencha?

Answer: ExtJS Sencha provides event listeners to handle events triggered by user interactions or system events. These listeners can be attached to components or application-level events.

Q6. What is data binding in ExtJS Sencha?

Answer: Data binding in ExtJS Sencha establishes a connection between a data source and a component, ensuring that changes in data automatically update the associated component.

Q7. How can you load data from a server using ExtJS Sencha?

Answer: ExtJS Sencha provides data stores that can be configured to load data from various sources such as JSON files, RESTful APIs, or XML.

Q8. How do you handle form validation in ExtJS Sencha?

Answer: ExtJS Sencha provides built-in form validation mechanisms. You can define validation rules for form fields and display validation messages accordingly.

Q9. What is the role of layouts in ExtJS Sencha?

Answer: Layouts in ExtJS Sencha define the structure and positioning of components within a container. They help in achieving responsive and flexible UI designs.

Q10. How can you handle asynchronous operations in ExtJS Sencha?

Answer: ExtJS Sencha provides various mechanisms to handle asynchronous operations, such as using Promises, callbacks, or utilizing the ExtJS Sencha data package.

Q11. Explain the concept of stores in ExtJS Sencha.

Answer: Stores in ExtJS Sencha act as data containers that hold and manage sets of records. They provide methods for data manipulation, filtering, sorting, and querying.

Q12. What is the difference between ExtJS Sencha Classic and Modern toolkits?

Answer: ExtJS Sencha Classic toolkit is focused on desktop-like applications, while the Modern toolkit is optimized for touch-based and mobile applications.

Q13. How can you customize the theme in ExtJS Sencha?

Answer: ExtJS Sencha allows customization of the theme using the SASS (Syntactically Awesome Style Sheets) preprocessor. You can modify variables, styles, and create custom themes.

Q14. What is the purpose of Sencha Cmd in ExtJS Sencha?

Answer: Sencha Cmd is a command-line tool used for various development tasks, such as generating applications, building, deploying, and managing ExtJS Sencha projects.

Q15. Explain the concept of view controllers in ExtJS Sencha.

Answer: View controllers in ExtJS Sencha handle the application logic associated with a specific view. They facilitate event handling, data manipulation, and communication between views.

Q16. How can you perform unit testing in ExtJS Sencha?

Answer: ExtJS Sencha provides the Sencha Test framework for unit testing. It allows developers to write test cases, execute them, and analyze the test results.

Q17. What is the purpose of the ExtJS Sencha data package?

Answer: The ExtJS Sencha data package provides powerful data handling and manipulation features, including data models, stores, proxies, and readers.

Q18. How can you handle routing and navigation in ExtJS Sencha?

Answer: ExtJS Sencha provides a routing mechanism that allows developers to define routes, handle URL changes, and navigate between different views in the application.

Q19. What is the concept of buffered rendering in ExtJS Sencha?

Answer: Buffered rendering in ExtJS Sencha improves the performance of large data sets by rendering only a portion of the data visible in the viewport, resulting in faster scrolling and rendering times.

Q20. How can you handle internationalization (i18n) in ExtJS Sencha?

Answer: ExtJS Sencha supports internationalization through localization files. Developers can define language-specific resources and switch between different locales dynamically.

Q21. Explain the concept of mixins in ExtJS Sencha.

Answer: Mixins in ExtJS Sencha allow code reuse and composition by combining reusable code segments into a single class. They help in implementing cross-cutting concerns.

Q22. How can you handle exception handling in ExtJS Sencha?

Answer: ExtJS Sencha provides a mechanism to handle exceptions using try-catch blocks. Additionally, ExtJS Sencha has error handling and reporting capabilities.

Q23. What is the purpose of the ViewModel in ExtJS Sencha?

Answer: The ViewModel in ExtJS Sencha connects the data layer with the view layer, providing data for binding and facilitating communication between the two.

Q24. How can you handle client-side data filtering in ExtJS Sencha?

Answer: ExtJS Sencha provides various methods to filter data in stores, including using filter functions, filter properties, or using the filterBy method.

Q25. What are the benefits of using ExtJS Sencha for web application development?

Answer: ExtJS Sencha offers a comprehensive set of tools and components that simplify web application development, provides excellent UI and UX, and supports cross-platform compatibility.