Consider a situation where you need to execute multiple asynchronous operations in sequence, each dependent on the result of the previous one. How would you implement this with Promises?
- Chaining Promises with .then()
- Promise.sequence()
- Promise.all()
- Async/Await
To execute multiple asynchronous operations in sequence, you would chain promises using .then(). This ensures that each operation is dependent on the result of the previous one. This approach maintains a clear and sequential flow in your asynchronous code.
How does the inclusion of "type": "module" in the package.json affect module resolution in Node.js?
- Enables ECMAScript module resolution
- Disables CommonJS module resolution
- Triggers automatic transpilation of modules
- Specifies module entry points
Including "type": "module" in package.json informs Node.js that the project uses ECMAScript modules. This affects module resolution by enabling the ECMAScript module resolution strategy, allowing the use of import and export statements.
How would you use static properties in a class representing a database connection to ensure there is only one connection instance?
- Implement a singleton pattern by allowing only one instance of the class and store the connection as an instance property.
- Utilize a static property to store the connection instance and check its existence before creating a new one.
- Use a separate connection manager class with a static property to handle the singleton behavior.
- Implement a global variable to store the connection instance and update it as needed.
To ensure there is only one instance of a database connection, using a static property within the class is appropriate. This static property can store the connection instance, and before creating a new connection, you can check if the static property already holds a valid connection. This approach aligns with the singleton pattern, ensuring a single point of access to the connection.
The spread operator can be effectively used to concatenate arrays without the use of traditional methods like '__________'.
- concat
- push
- join
- spread
The spread operator (...) can be used to concatenate arrays in a concise way. It allows you to spread the elements of one array into another, effectively achieving concatenation without using traditional methods like concat, push, or join.
What is the role of the .catch() method in Promise chaining?
- It is used to handle errors that occur in the promise chain.
- It is only applicable to synchronous code.
- It can only be used once in a promise chain.
- It must always be placed before any .then() block.
The .catch() method in Promise chaining is used to handle errors that occur anywhere in the promise chain. It ensures that errors are caught and appropriate actions are taken to handle them gracefully.
To import only a part of a module, use the __________ syntax in ES6.
- import {specificPart} from
- include {specificPart} from
- load {specificPart} from
- require {specificPart} from
In ES6, when importing only a part of a module, you use the {} syntax. For example, import {specificPart} from 'moduleName'; allows you to import only the specified part of the module.
When using Promises with AJAX, handling network errors is done through the ______ method of the Fetch API.
- error
- fail
- catch
- reject
When using Promises with AJAX, handling network errors is done through the catch method of the Fetch API. The catch block allows you to handle any errors that occurred during the AJAX request.
How can functional composition benefit the readability and maintainability of JavaScript code?
- Enhances code modularity
- Reduces side effects
- Encourages reuse of functions
- All of the above
Functional composition involves combining small, pure functions to create more complex ones, enhancing modularity, reducing side effects, and promoting code reuse. This leads to improved code readability and maintainability.
Named exports are useful for ___________ functionality across modules.
- hiding
- sharing
- encapsulating
- extending
Named exports in ES6 allow you to share specific functionalities across modules. It is a way to expose selected parts of a module to be used in other modules, making option b) sharing the correct answer.
To ensure all errors are caught in an async function, use try/catch along with ________.
- async/await
- catch/error
- reject/resolve
- throw/catch
When working with asynchronous code in JavaScript, using try/catch blocks along with async/await ensures that errors within the async function are properly caught and handled.
Can currying be applied to asynchronous functions in JavaScript? How?
- Yes, by using libraries like Lodash
- No, currying is applicable only to synchronous functions
- Yes, by returning a promise from each curried function
- Yes, by using the async/await syntax in each curried function
Currying can be applied to asynchronous functions by returning a promise from each curried function. This allows composing asynchronous operations in a modular and readable manner.
For a function that calculates a discount on a price, how can default parameters be used to make the function adaptable to different discount strategies?
- Use default parameters to set a default discount strategy, like calculateDiscount(price, discount = 0.1).
- Allow users to pass a discount strategy as a parameter and use default parameters to handle cases where no strategy is provided.
- Utilize default parameters for individual discount components, such as percentage and fixed amount, offering flexibility in discount calculation.
- Set default parameters for both price and discount strategy, allowing users to calculate discounts with a default strategy or a custom one.
Default parameters can enhance the adaptability of a discount calculation function. By setting a default discount strategy, users have the option to either accept the default or provide a custom strategy. This design allows for a default behavior while accommodating different discount strategies based on user preferences or specific use cases.