When an EventEmitter instance experiences an error, the typical event that is emitted is ______.
- 'error'
- 'exception'
- 'fail'
- 'warning'
In Node.js, when an EventEmitter instance experiences an error, the typical event that is emitted is 'error'. This event allows you to handle errors that occur within event listeners attached to the EventEmitter.
How does the closure concept relate to higher-order functions in JavaScript?
- Closures are only used in lower-order functions.
- Higher-order functions cannot create closures.
- Higher-order functions often return closures, allowing them to encapsulate and manage private data.
- Closures are unrelated to higher-order functions.
Closures and higher-order functions are closely related in JavaScript. Higher-order functions often return closures, which can encapsulate and manage private data, creating a powerful mechanism for maintaining state and data privacy.
If an error is not handled by custom error-handling middleware in Express, it is handled by the ______.
- next()
- defaultErrorHandler
- express.handleError()
- console.error()
If an error is not handled by custom error-handling middleware in Express, it is handled by the default Express error handler, which is often referred to as the "defaultErrorHandler." This handler sends an error response to the client and logs the error details.
How does the spread operator behave when used with JavaScript objects that have the same properties?
- It merges the properties, with the values of the second object overwriting the values of the first object.
- It throws an error because objects with the same properties cannot be spread.
- It combines the properties into an array.
- It creates a new object with the properties of the first object only.
When the spread operator (...) is used on objects with the same properties, it merges the properties, with the values of the second object overwriting the values of the first object. This behavior is known as object property spreading.
You are tasked with optimizing the build process for a production environment. What considerations should you make regarding the management of dependencies and devDependencies?
- Include all dependencies in devDependencies
- Minimize the use of dependencies
- Exclude devDependencies in production builds
- Always use the latest version of dependencies
In a production build, it's important to exclude devDependencies as they are typically only needed for development and testing. Including them in production builds can increase the size of the application unnecessarily. Option (2) is a good practice, but not directly related to managing dependencies for production. Option (1) is incorrect as including all dependencies in devDependencies is not a best practice for production builds. Option (4) is risky as it may introduce compatibility issues.
How can you create a buffer instance in Node.js?
- new Buffer(10)
- Buffer.alloc(10)
- createBuffer(10)
- buffer.create(10)
In Node.js, you can create a buffer instance using the Buffer.alloc(size) method, where size is the desired size of the buffer in bytes. The new Buffer() constructor is deprecated, and the other options are not valid ways to create a buffer in Node.js.
In which scenario is a full-text search most appropriately used?
- Searching for specific keywords within a large body of text
- Searching for structured data in a database
- Searching for filenames in a file system
- Searching for numerical values in a spreadsheet
Full-text search is most appropriately used when searching for specific keywords within a large body of text, such as searching for documents or articles containing certain words or phrases. It allows for complex text-based queries, making it ideal for content-heavy applications.
To add an item to the beginning of an array in JavaScript, you can use the ______ method.
- push
- unshift
- append
- insert
In JavaScript, you can use the unshift method to add an item to the beginning of an array. The push method adds an item to the end of an array. append and insert are not native array methods in JavaScript.
What is the primary purpose of using an ORM (Object-Relational Mapper) like Sequelize in a project?
- To facilitate database interactions by mapping JavaScript objects to database tables
- To create user interfaces for web applications
- To optimize code for better performance
- To secure API endpoints
The primary purpose of using an Object-Relational Mapper (ORM) like Sequelize is to facilitate database interactions by mapping JavaScript objects to database tables. It abstracts the underlying database, making it easier to work with databases and reducing the need for writing raw SQL queries. The other options are not the primary purposes of an ORM.
n CRUD operations, which operation is used to modify existing data?
- Create
- Read
- Update
- Delete
The Update operation in CRUD (Create, Read, Update, Delete) operations is used to modify existing data in the system. It allows you to make changes to existing records.