In a single-page application, how can dynamic imports optimize loading times for different components?
- Load components synchronously in the main bundle.
- Use dynamic imports to load components lazily when they are needed.
- Preload all components during the initial page load.
- Use static imports to include all components in the main bundle.
Dynamic imports allow loading components asynchronously when they are needed, reducing the initial loading time and improving performance. This is particularly useful in single-page applications where not all components are required immediately.
What method would you use to get the number of elements in a Map?
- size method
- length method
- count method
- elements method
To get the number of elements in a Map in ES6, you would use the size method. This method returns the number of key-value pairs present in the Map.
When using super in a constructor, it initializes the _______ of the derived class.
- Properties
- Constructor
- State
- Methods
In a derived class constructor, super initializes the properties of the derived class, calling the constructor of the parent class. This sets up the state for the derived class.
What is a key feature of arrow functions regarding the handling of the this keyword?
- They bind the this keyword dynamically
- They do not have access to the this keyword
- They always refer to the this of the global object
- They bind the this keyword statically
Arrow functions do not have their own this context; instead, they inherit the this value from the surrounding lexical scope. This is a crucial feature that can prevent the common issue of losing the correct this context in nested functions.
What is a higher-order function in JavaScript?
- A function that takes another function as an argument.
- A function that operates on other functions, either by taking them as arguments or by returning them.
- A function that only performs operations on numbers.
- A function that can only be called once.
In JavaScript, a higher-order function is one that either takes a function as an argument or returns a function. This allows for the creation of more flexible and reusable code.
To insert a variable into a template literal, use the ${} __________.
- Parentheses ()
- Curly braces {}
- Square brackets []
- Angle brackets <>
To insert a variable into a template literal, use the ${} syntax with curly braces. This allows for dynamic content within the string, making it more flexible and readable.
Static methods are often used for _________ that are relevant to all instances of a class.
- Properties
- Functionality
- Events
- Callbacks
In object-oriented programming, static methods are associated with a class rather than instances. They are often used for functionality that is relevant to all instances of a class, rather than a specific instance. This helps in organizing code and improving code readability.
Can you access instance properties from a static method?
- Yes, using the this keyword.
- No, it results in a runtime error.
- Yes, using the super keyword.
- No, instance properties are inaccessible.
No, you cannot access instance properties directly from a static method. Static methods are associated with the class itself and do not have access to instance-specific data. Option D is correct.
What is a mixin in the context of JavaScript ES6?
- A way to create variables in ES6
- A function that takes two objects and returns a new object
- A method for adding properties and methods to a class
- A type of loop in ES6
In JavaScript ES6, a mixin is a way to compose classes by adding properties and methods to a class. It allows the reuse of functionalities and promotes code reusability. Unlike inheritance, mixins do not rely on a hierarchical relationship between classes. They enhance the flexibility and maintainability of code.
How do default parameters interact with destructuring assignment in function arguments?
- They can't be used together
- Destructuring assignment takes precedence
- The function ignores the default parameters
- Destructuring is not supported in ES6
Default parameters and destructuring can be used together, and destructuring takes precedence. Explanation should elaborate on how they work together.