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.
The Access-Control-Allow-Methods header in CORS specifies which HTTP ________ are allowed.
- methods
- verbs
- headers
- origins
The Access-Control-Allow-Methods header in CORS specifies which HTTP methods are allowed for cross-origin requests. It should include a comma-separated list of HTTP methods such as GET, POST, PUT, DELETE, etc.
How can you compare two buffers in Node.js to check if they are equal?
- Using the == operator
- Using the compare() method
- By converting them to strings and using ===
- Using the isEqual() function
To compare two buffers in Node.js, you should use the compare() method. The == operator and === with string conversion won't provide accurate results, and there's no isEqual() function for buffers in Node.js.
In which format is image data usually sent to the server when uploading files in a web application?
- JSON
- XML
- Base64
- CSV
Image data is usually sent to the server in Base64 format when uploading files in a web application. This format allows binary data (like images) to be represented as a string, making it easier to transmit as part of an HTTP request. The other options (JSON, XML, and CSV) are not typically used for sending binary data like images.
Which of the following is a common technique used for optimizing database queries?
- Query caching
- Adding more indexes
- Increasing database complexity
- Ignoring query performance
One common technique used for optimizing database queries is query caching. It involves storing frequently used query results in memory, reducing the need to re-execute the same query, and improving response times.
If a package is required for running the tests, it should ideally be listed under ________.
- devDependencies
- dependencies
- peerDependencies
- optionalDependencies
If a package is required for running the tests, it should ideally be listed under devDependencies. This ensures that the testing dependencies are only installed during development and testing phases, keeping the production environment clean from unnecessary packages.
You are designing a logging system in Node.js where multiple loggers are listening to logging events. How would you manage and optimize the event listeners to avoid potential memory leaks?
- event.setMaxListeners(1)
- event.on('log', loggerCallback)
- event.prependListener('log', loggerCallback)
- event.removeListener('log', loggerCallback)
To avoid memory leaks when multiple loggers are listening to logging events, it's crucial to remove listeners when they are no longer needed. The event.removeListener() method should be used to remove specific listeners, ensuring that you free up memory and resources when loggers are no longer required. The other options are related to listener management but do not directly address memory leaks.
In ESLint, the ______ property in the configuration file can be used to define global variables.
- Globals
- Environment
- Globals
- Rules
In ESLint, the globals property in the configuration file is used to define global variables that are accessible throughout your code without triggering linting errors. This allows you to specify variables that are declared externally or provided by the environment. The environment option is used to specify which environments your code runs in, but it's not used to define individual global variables. The rules property is used for configuring ESLint rules.