Why is input validation crucial in web development?
- To ensure data is entered correctly.
- To make web forms look more attractive.
- To increase website loading speed.
- To prevent SQL injection.
Input validation is crucial in web development to prevent security vulnerabilities like SQL injection and to ensure that the data entered by users is correct and safe. It helps protect against malicious input and maintain data integrity.
You are tasked with improving the reliability of a large codebase. Using Jest, how would you approach writing tests for functions with side effects like database calls or API requests?
- Use Jest's mocking capabilities to create mocks or spies for database and API calls.
- Skip testing functions with side effects; focus on pure functions.
- Manually perform database/API calls in tests to ensure real-world reliability.
- Use only integration tests for functions with side effects.
To improve reliability and isolate side effects, you should use Jest's mocking capabilities to create mocks or spies for database and API calls. This way, you can control and verify the behavior of these calls without involving the actual database or API. The other options may lead to unreliable tests or skipped testing.
When a package is listed under devDependencies, it means that the package is only required during the ________ of the application.
- development
- deployment
- testing
- runtime
When a package is listed under devDependencies, it means that the package is only required during the development of the application. These are typically tools and libraries used for development, such as testing frameworks, build tools, and linters. They aren't needed in the production or deployment environment.
You are tasked with developing a function to flatten a nested array structure. Which method would you use to flatten the arrays efficiently?
- Recursive function
- Array.prototype.flatMap()
- Nested loops
- Array.prototype.concat()
To efficiently flatten a nested array structure, you can use Array.prototype.flatMap(). It not only flattens the array but also allows you to transform its elements if needed. Using recursion is an option but can lead to stack overflow errors for deeply nested arrays.
In which of the following template engines can you write plain JavaScript code inside special tags?
- Mustache
- Handlebars
- Pug
- EJS (Embedded JavaScript)
EJS (Embedded JavaScript) allows you to write plain JavaScript code inside special tags <% %> or <%= %>. This feature is useful for executing JavaScript logic and generating dynamic content within templates. Mustache, Handlebars, and Pug have their own template syntax and do not support this feature in the same way.
Which of the following Node.js modules would you typically use to handle file uploads?
- fs
- http
- url
- multer
In Node.js, to handle file uploads, you would typically use the multer module. multer is a middleware for handling multipart/form-data, which is the format used for file uploads. The other options (fs, http, and url) are commonly used for different purposes, such as working with files, creating HTTP servers, and parsing URLs, respectively.
When using ES6+ modules, the import statement must be at the ________ of the file.
- bottom
- middle
- top
- end
When using ES6+ modules, the import statement must be at the top of the file. This is because ES6+ modules have a strict structure, and imports are processed before the module's code is executed. Placing the import statement at the top ensures that the imported dependencies are available throughout the module.
Which of the following is required to serve static files in an Express application?
- express.static()
- app.static()
- serveStatic()
- staticFiles()
In Express.js, the express.static() middleware is used to serve static files like HTML, CSS, and JavaScript files. This middleware is essential to handle static assets in an Express application. The other options are not valid methods for serving static files.
What is the primary purpose of using ESLint in a JavaScript project?
- Ensure code quality and enforce coding style
- Execute JavaScript code
- Debug JavaScript code
- Optimize JavaScript code
ESLint is primarily used to ensure code quality and enforce coding style standards in a JavaScript project. It helps identify and fix coding style issues, potential bugs, and maintainability problems in your codebase.
What would happen if you do not use the express.static middleware function for serving static files?
- Static files would be served by default.
- You cannot serve static files in Express.js.
- Express.js would throw an error.
- Static files would be served but with limited caching.
If you do not use the express.static middleware function to serve static files, Express.js would not be able to serve static files by default. You need this middleware to handle static file requests. The other options are incorrect because Express.js does have the capability to serve static files, but you need to configure it properly.