When using dynamic imports, the import() function returns a ________.
- Promise
- Callback
- Function
- Object
When using dynamic imports in JavaScript, the import() function returns a Promise. This Promise resolves to the module's namespace object once the module is loaded and ready for use.
What is the primary purpose of the package-lock.json file in a Node.js project?
- To store documentation for the project
- To store a backup of the package.json file
- To specify the version of Node.js to use
- To lock the version of each package's dependencies
The primary purpose of the package-lock.json file in a Node.js project is to lock the version of each package's dependencies. This ensures that every developer working on the project uses the same versions of dependencies, preventing version conflicts and ensuring consistency across environments. The other options (To store documentation for the project, To store a backup of the package.json file, and To specify the version of Node.js to use) do not accurately describe the purpose of the package-lock.json file.
How do you correctly implement a middleware function in Express.js?
- Define a function with the signature (req, res)
- Use the middleware() keyword before a route definition
- Import the express-middleware module
- Add a next() function to the route handler
To correctly implement a middleware function in Express.js, you define a function with the signature (req, res). This function can also take an optional next parameter if you want to pass control to the next middleware in the stack. The (req, res) signature allows you to access and modify the request and response objects.
What is the main difference between SQL and NoSQL databases regarding data structure?
- SQL databases are faster than NoSQL databases.
- SQL databases are faster than NoSQL databases.
- SQL databases are limited to relational data, while NoSQL databases can handle any data type.
- SQL databases are open source, while NoSQL databases are proprietary.
The main difference is that SQL databases use a structured, tabular format for data storage, adhering to a fixed schema, while NoSQL databases use various flexible data models, making them suitable for unstructured or semi-structured data. SQL databases are not inherently faster, and the choice depends on the specific use case.
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.
You are tasked with iterating over an array and modifying each element. Which loop structure would be the most suitable, considering the modern ECMAScript standards and why?
- for loop
- while loop
- for...in loop
- for...of loop
In modern ECMAScript standards, the for...of loop is the most suitable for iterating over an array and modifying each element. It provides a cleaner syntax and avoids issues with unexpected behavior that can occur with the for...in loop when working with arrays. The for loop and while loop are also options, but the for...of loop is more concise and specifically designed for array iteration.
In JavaScript, the import statement cannot be used in ________.
- functions
- classes
- conditionals
- loops
In JavaScript, the import statement cannot be used inside conditionals (e.g., if statements or loops). It must be used at the top level of a module. This is because module imports are processed before the code is executed, and conditionals are not allowed to change the module structure dynamically.
What is the primary purpose of running the npm init command in a Node.js project?
- To install Node.js
- To create a new Node.js project
- To update Node.js packages
- To uninstall Node.js
The primary purpose of running npm init in a Node.js project is to create a new Node.js project. This command initializes a package.json file, which is essential for managing project dependencies and configurations. It does not install or uninstall Node.js itself.
In Node.js, a buffer can be converted to JSON using the ______ method.
- toJSON
- bufferToJSON
- JSON.stringify
- serialize
To convert a buffer to JSON in Node.js, you can use the JSON.stringify method. This method will create a JSON string representation of the buffer's contents.
How can you ensure the reliability of your tests in a scenario where external services have inconsistent behavior?
- Mock the external services to simulate consistent behavior; Use retry mechanisms in your tests to account for inconsistencies; Write tests that ignore external services.
- Rely on external services' behavior as is, without any mitigation; Run the tests at a specific time when external services are expected to be consistent; Ignore testing external services.
- Always use real external services in your tests to ensure accuracy; Write tests that fail gracefully when external services are inconsistent; Run tests with random intervals to catch inconsistencies.
- Use external services only for integration tests, not unit tests; Write tests that expect failures due to external services; Use only internal services to avoid inconsistencies.
To ensure test reliability when external services have inconsistent behavior, it's best to mock the external services to simulate consistent behavior during tests. The other options either ignore the issue or rely on unpredictable external behavior.