Developers can use npm deprecate [@] to mark a package or a specific version as deprecated, displaying a warning message ______ to any developers installing it.
- internally
- externally
- globally
- locally
When using npm deprecate, the correct option is externally. This means that a deprecation warning message will be displayed to any developers installing the package from outside the project.
How does JavaScript handle implicit data type conversion?
- JavaScript automatically converts data types when performing certain operations, which can lead to unexpected results.
- JavaScript throws errors when trying to perform operations on different data types.
- JavaScript prohibits implicit data type conversion to ensure data consistency.
- JavaScript only allows explicit data type conversion using built-in functions.
JavaScript performs implicit data type conversion, also known as type coercion, when operators or functions are used with values of different data types. This can lead to unexpected behavior, so it's important to understand how type coercion works in JavaScript.
How does Content Security Policy (CSP) help in preventing XSS attacks, and what are its limitations?
- CSP restricts the usage of third-party libraries
- CSP blocks all JavaScript execution
- CSP defines rules for resource loading and script execution
- CSP is ineffective against XSS attacks
Content Security Policy (CSP) helps prevent Cross-Site Scripting (XSS) attacks by defining rules for resource loading and script execution in web applications. It can restrict the sources from which scripts can be executed, mitigating the risk of malicious script injection. However, CSP has limitations, such as its inability to prevent all forms of XSS attacks, the need for careful configuration, and potential compatibility issues with legacy code.
How can you match routes with a specific pattern in Express.js?
- app.pattern('/route', callback)
- app.match('/route', callback)
- app.use('/route', callback)
- app.get('/route', callback)
In Express.js, you can use the app.get('/route', callback) method to match routes with a specific pattern. The get method is used to handle HTTP GET requests and is often used to define routes with specific patterns. The other options do not represent the standard way to define route patterns in Express.js.
How can you handle error responses in Express for cleaner error reporting?
- Using the throw statement
- Using the try...catch block
- Implementing custom error handling middleware
- Ignoring errors for cleaner logs
To handle error responses in Express for cleaner error reporting, you can implement custom error handling middleware. This middleware can catch errors and provide a standardized way to handle and respond to them, improving error reporting and debugging.
You are developing a suite of unit tests for a service that interacts with an external API. How would you employ mocking and stubbing to ensure the tests are isolated and reliable?
- Mock the external API calls to simulate responses
- Stub all internal functions used in the service
- Avoid mocking and use real external API calls
- Mock only the database interactions
In unit testing, it's crucial to isolate the code being tested. To ensure tests are isolated and reliable when dealing with an external API, you should mock the external API calls. This allows you to control the responses and not rely on external services during tests. Stubbing internal functions is not the primary approach for isolating external API calls. Avoiding mocking by using real API calls can lead to unreliable and slow tests. Mocking the database, in this case, is unnecessary.
You are configuring a Node.js project and want to ensure that a certain command runs before your tests run each time. How would you configure this using the package.json file?
- Use the "pretest" script in the "scripts" section of the package.json file to specify the command that should run before tests.
- Include the command in the "description" field of the package.json file.
- Create a separate pretest.json configuration file.
- Use a comment in the test file to specify the pretest command.
To ensure a certain command runs before tests each time, you should use the "pretest" script in the "scripts" section of the package.json file. This script will be executed automatically before running tests when the npm test command is invoked. The other options are not standard ways to configure pretest actions.
You are tasked with developing a logging system for an Express.js application to log every incoming request. How would you implement middleware to log the details of every request made to the application?
- Create a middleware function that logs request details and use app.use to apply it globally to all routes.
- Include logging code within each route handler to log request details individually.
- Use a third-party logging library like Morgan and configure it within your Express.js application.
- Use JavaScript's built-in console.log within each route to log request details.
To log details of every incoming request in an Express.js application efficiently, you should create a dedicated middleware function that logs request details and use app.use to apply it globally to all routes. This centralizes logging and avoids duplicating code in each route handler. The other options are either less efficient or not recommended for production applications.
How can you install ESLint in your Node.js project?
- Using npm or yarn: npm install eslint --save-dev or yarn add eslint --dev
- Downloading it from the official website
- Installing it globally using npm install -g eslint
- Adding it directly to your HTML file
You can install ESLint in your Node.js project using npm or yarn by running the command npm install eslint --save-dev or yarn add eslint --dev. This ensures that ESLint is added as a development dependency for your project.
Which of the following is a suitable method to prevent variable leakage in the global scope?
- Using the var keyword to declare variables.
- Using immediately-invoked function expressions (IIFE).
- Using global variables exclusively.
- Using let and const keywords to declare variables.
Using immediately-invoked function expressions (IIFE) is a common technique to prevent variable leakage into the global scope. It encapsulates variables within a function scope, avoiding global pollution. The other options do not address this concern effectively.
When using the map method on an array in JavaScript, the original array ______ be mutated.
- may
- will
- must
- can't
When using the map method on an array in JavaScript, the original array can't be mutated. The map method creates a new array with the results of calling a provided function on every element in the original array without changing the original array itself.
What happens when you try to access an index in a buffer that does not exist in Node.js?
- It returns null
- It throws an "IndexOutOfRange" error
- It returns an "undefined" value
- It automatically resizes the buffer
When you try to access an index in a buffer that does not exist, Node.js throws an "IndexOutOfRange" error. Buffers do not automatically resize.