How can enhanced object literals in ES6 improve the process of creating objects that inherit from another object?
- Facilitates concise syntax for defining the prototype chain
- Enables automatic inheritance through the extends keyword
- Introduces mixins for flexible composition of properties
- Provides a dedicated Object.extend method for inheritance
Enhanced object literals in ES6 simplify the process of creating objects that inherit from another object by providing a concise syntax for defining the prototype chain. This concise syntax enhances code readability and reduces the boilerplate code associated with prototype-based inheritance, making it more accessible and efficient.
The __________ file in a module directory helps in defining the entry point for the module in ES6.
- main.js
- module.js
- index.js
- entry.js
In ES6, the index.js file serves as the default entry point for a module within a directory. It is automatically recognized when importing the module.
Can you use the arguments object inside an arrow function?
- Yes, arrow functions have access to the arguments object
- No, arrow functions do not have access to the arguments object
- Only if the arrow function is declared with the 'arguments' keyword
- Yes, but only in strict mode
Arrow functions do not have their own 'arguments' object. They inherit it from the enclosing scope, which may lead to unexpected behavior. Option B is correct.
How does the temporal dead zone affect variables declared with let and const?
- Variables become undefined
- Variables are hoisted to the top of the scope
- Variables cannot be reassigned
- Variables retain their initial value
The temporal dead zone is a phase during which variables declared with let and const exist but cannot be accessed or assigned. Attempting to use such variables before their declaration results in a ReferenceError. However, the variables are hoisted, meaning their declarations are moved to the top of the scope, but their assignments remain in place. This affects the behavior of code and is crucial to understand for avoiding bugs.
What are the implications of not calling super() in a derived class constructor?
- It has no implications
- It results in a syntax error
- It prevents the derived class from inheriting properties and methods
- It leads to a runtime error
Omitting 'super()' in a derived class constructor prevents proper initialization of the object and may lead to unexpected behavior, as the parent class constructor is not invoked. This can cause issues in inheriting properties and setting up the object's state correctly.
To handle both success and failure in an AJAX call using Promises, use .then() for success and _______ for errors.
- .error()
- .catch()
- .fail()
- .reject()
In Promises, .then() is used for success, and .catch() is used for handling errors. The .catch() method is specifically designed to handle the rejection of a promise, making it the correct choice in this scenario.
In ES6, what is the role of the 'package.json' file in module resolution?
- Defines dependencies and module paths
- Specifies the version of ECMAScript used
- Configures package settings
- Determines the module's entry point
The 'package.json' file in ES6 modules plays a crucial role by defining dependencies and specifying module paths. It helps in resolving modules and managing project dependencies effectively. Knowing how 'package.json' influences module resolution is essential for maintaining a well-structured project.
What is a key difference between a JavaScript Object and a Map?
- Properties order, properties, ordering, key-value pairs
- Key-value pairs, properties, ordering, properties order
- Properties order, properties, key-value pairs, ordering
- Key-value pairs, ordering, properties order, properties
In JavaScript, the key difference between an Object and a Map lies in the ability to use any data type as the key in a Map, providing a more flexible and reliable data structure for certain use cases. While Objects are limited to string and symbol keys, Maps allow any data type as keys, allowing for better handling of key-value pairs.
In ES6, you can directly assign ________ to object properties without repeating the variable name.
- Destructuring
- Shorthand Notation
- Computed Property Names
- Arrow Functions
In ES6, destructuring allows you to directly assign values from objects or arrays to variables, making code concise and readable. Shorthand notation is commonly used for this purpose.
When destructuring function parameters, _________ can be used to handle undefined input.
- Default parameter
- Optional chaining
- Nullish coalescing
- Early binding
When destructuring function parameters, the correct option is the "Default parameter." Default parameters in JavaScript allow you to provide a default value for a function parameter if no value or undefined is passed. This helps in handling undefined input gracefully.
What are the implications of using default parameters on function length property?
- The length property reflects the number of parameters without default values
- The length property includes parameters with default values
- Default parameters do not affect the length property
- The length property is no longer relevant with default parameters
When default parameters are used in a function, they do not contribute to the length property. The length property only counts the number of parameters without default values. Therefore, the length might not accurately represent the total number of arguments the function can accept.
In ES6, mixins can be created by a function that takes a _________ as an argument and extends it.
- Class
- Function
- Object
- Module
In ES6, mixins are created by a function that takes an object as an argument and extends it. This approach allows for dynamic composition, enabling the combination of functionalities from different sources into a single object.