What is the purpose of the this keyword in JavaScript?
- Refers to the current function's scope
- Refers to the current instance or object
- Refers to the global scope
- Refers to the parent function's scope
In JavaScript, the this keyword refers to the current instance or object. Its value depends on how a function is called and is often used in object-oriented programming.
What is memoization and how is it used for optimizing function performance in JavaScript?
- A design pattern for creating dynamic web components
- A method for encrypting sensitive data in JavaScript
- A technique to cache and reuse the results of expensive function calls
- An approach to asynchronous programming in JavaScript
Memoization is a technique in JavaScript used to cache and reuse the results of expensive function calls. By storing the results of expensive function calls and returning the cached result when the same inputs occur again, it helps optimize overall function performance.
The CSS margin property controls the _______ of an element.
- Alignment
- Padding
- Spacing
- Width
The CSS margin property controls the spacing of an element. It defines the space outside the element's border, providing separation from other elements.
Which of the following is not a primitive data type in JavaScript?
- boolean
- number
- object
- string
In JavaScript, object is not a primitive data type. It is a complex data type used to store collections of key-value pairs. The primitive data types are number, boolean, and string.
You're experiencing slow performance on a web page. How would you utilize Browser Developer Tools to diagnose and address the issue?
- Check the Network tab for slow-loading resources, analyze waterfall charts, and identify bottlenecks
- Inspect the Elements panel for layout issues
- Monitor the Performance tab for memory leaks
- Use the Console tab to debug JavaScript code
When experiencing slow performance, the Network tab in Browser Developer Tools helps identify slow-loading resources, analyze waterfall charts, and pinpoint bottlenecks causing the issue.
In large-scale web applications, which server-side language is often preferred for its scalability, support for microservices architecture, and compatibility with frameworks like Sinatra and Rails?
- Java
- Node.js
- Python
- Ruby
Ruby is often preferred in large-scale web applications for its scalability, support for microservices architecture, and compatibility with frameworks like Sinatra and Rails. Its elegant syntax and convention-over-configuration principle make it suitable for rapid development.
Which meta tag is used to make a webpage responsive on various devices?
The correct meta tag for making a webpage responsive is . It configures the viewport settings, allowing the page to adapt to the device's width.
Which design pattern separates the responsibilities of creating complex objects and the objects themselves?
- Abstract Factory
- Builder
- Prototype
- Singleton
The Builder design pattern separates the construction of a complex object from its representation. It allows the same construction process to create different representations, promoting flexibility and reusability.
You're working on a web application where user authentication is crucial. How would you handle authentication errors securely?
- Implementing OAuth2 with JWT tokens
- Sending authentication details in query parameters
- Storing plaintext passwords in the database
- Using HTTP basic authentication
Implementing OAuth2 with JWT tokens is a secure method for handling authentication errors. OAuth2 provides a standardized framework for authentication, and JWT tokens add an extra layer of security by encoding information.
In a CI/CD pipeline, the process of automatically deploying changes to production after passing tests is known as Continuous _______.
- Delivery
- Deployment
- Integration
- Testing
Continuous Deployment (CD) is the process of automatically deploying code changes to production after they have passed all necessary tests in the CI/CD pipeline. This ensures a smooth and efficient release process.