Consider a scenario where you have an iterable data structure with complex logic for each iteration. How would using a for...of loop simplify or complicate the implementation?
- It would simplify the implementation.
- It would complicate the implementation.
- It would have no impact on the implementation.
- It depends on the specific logic involved.
The correct option is "It would simplify the implementation." The for...of loop is designed to iterate over iterable objects, and its syntax is concise and clear. When dealing with complex logic for each iteration, using for...of can enhance code readability and maintainability by focusing on the logic rather than the mechanics of iteration.
In a large-scale application with multiple JavaScript modules, how would you apply tree shaking to reduce the size of the deployed bundle?
- Use a bundler like Webpack that supports tree shaking.
- Manually remove unused code from each module.
- Convert the modules to CommonJS format.
- Utilize a code minification tool.
Tree shaking involves removing dead code during the bundling process. Webpack, a popular bundler, has built-in support for tree shaking, making it an efficient choice. Manually removing code or changing the module format is not the standard approach for tree shaking. Code minification is related but doesn't specifically address dead code elimination.
Recursive functions can be used effectively for tasks such as __________ traversal in data structures.
- Depth-first
- Breadth-first
- Pre-order
- Post-order
Recursive functions are commonly employed for depth-first traversal, where the function explores as far as possible along each branch before backtracking.
What happens to the entries in a WeakMap when there are no other references to the key?
- They are automatically removed from the WeakMap
- They are retained in the WeakMap
- They trigger an error
- They are marked for deferred removal
In a WeakMap, entries are automatically removed when there are no other references to the key. This behavior makes WeakMap suitable for scenarios where memory management is crucial, and entries should be tied to the existence of their key elsewhere in the program.
Q1: In a project where you are required to create multiple types of user profiles, how would you use prototypes to ensure code reusability and efficiency?
- Utilize Object.create()
- Use Object.assign()
- Employ class inheritance
- Implement mixin patterns
Prototypes play a crucial role in JavaScript's object-oriented design. Utilizing mixin patterns allows you to compose functionalities from multiple objects, ensuring modular and reusable code. This approach helps in creating diverse user profiles by combining specific traits through prototypes.
What is the purpose of the "module" field in a package.json file in an ES6 project?
- Enables the use of ECMAScript modules
- Specifies the version of ECMAScript
- Declares the project as a Node.js module
- Defines the project as an ES6 project
The "module" field in package.json is used to indicate that the project is using ECMAScript modules. This allows the use of the import and export statements in the project. It is crucial for enabling the ES6 module system in Node.js and browsers.
In a scenario where you need to create a custom data structure (like a tree), how would you make it iterable?
- Implement the iterable protocol by defining a Symbol.iterator method
- Use the Array.from() method to convert the data structure to an array
- Utilize the for...in loop to iterate over the data structure
- Create a custom iterate method for the data structure
Making a custom data structure iterable involves implementing the iterable protocol by defining a Symbol.iterator method. This method should return an iterator object with a next method, allowing the data structure to be iterated using the for...of loop or other iterable mechanisms in JavaScript.
In a web application with heavy DOM manipulations and API calls, how would the event loop and call stack manage these operations?
- The event loop ensures that asynchronous operations, like API calls, are offloaded to the browser's APIs and queued in the task queue. The call stack, which handles synchronous operations, prioritizes execution of tasks in the stack.
- The call stack manages synchronous operations, and the event loop coordinates the execution of asynchronous operations, ensuring they don't block the main thread.
- The call stack processes synchronous tasks, and the event loop continuously checks the call stack and task queue, prioritizing tasks based on their readiness for execution.
- The event loop delegates asynchronous tasks to the browser's APIs, which are executed separately from the main threaThe call stack manages synchronous tasks, preventing them from blocking the execution flow.
In a web application, the event loop and call stack work in tandem. The event loop coordinates asynchronous operations, preventing them from blocking the main thread. The call stack manages synchronous tasks, and the event loop offloads asynchronous tasks to the browser's APIs. Understanding this interaction is crucial for optimizing performance in applications with heavy DOM manipulations and API calls.
How does error propagation work in a Promise chain?
- Propagates to the nearest catch block
- Propagates to the outermost catch block
- Propagates to the nearest then block
- Propagates to the global error handler
In a Promise chain, errors propagate to the nearest catch block. If there isn't a catch block in the immediate chain, it continues to propagate outward until it finds one. This behavior allows for more granular error handling based on where the error occurs in the chain.
In ES6, what is the difference between declaring methods in a class and in an object literal?
- Methods in a class are enumerable, while methods in an object literal are not
- Methods in a class are prototype methods, while methods in an object literal are not
- There is no difference between declaring methods in a class and in an object literal
- Methods in an object literal have access to the 'super' keyword
The key distinction is that methods in a class are prototype methods, meaning they are shared among all instances of the class. In contrast, methods in an object literal are not shared among instances.
If a property is not found on an object, JavaScript looks up the property on the object's prototype, known as the _________ chain.
- Prototype
- Scope
- Inheritance
- Execution
In JavaScript, the process of searching for a property involves traversing the prototype chain. If the property is not found on the object, it looks up in the prototype chain until it finds the property.
How does the 'use strict' mode affect class behavior in ES6?
- It enforces stricter type checking in class properties
- It allows for dynamic addition of properties in a class
- It has no impact on class behavior
- It throws an error if the class contains undeclared variables
In 'use strict' mode, the class behavior becomes more rigid. It disallows the usage of undeclared variables, ensures that the 'this' keyword behaves more predictably, and generally promotes safer coding practices.