Important Concepts Flashcards

Question

What is the spread operator in JavaScript?

Answer 1

The spread operator (...) allows you to expand an iterable (e.g. an array or a string) into its individual elements. It can be used to create a new array or to merge multiple arrays.

Answer 2

Default parameters are a feature of JavaScript that allows you to specify default values for function parameters. This means that if a value is not passed for a particular parameter, the default value will be used instead.

Answer 3

A Map is a collection of key-value pairs. It is a built-in object that allows you to easily store, access, and update data. Maps are similar to objects, but they have some additional functionality and are more efficient for certain use cases.

Answer 4

A Set is a collection of unique values. It is a built-in object that allows you to easily store, access, and update data. Sets are similar to arrays, but they only store unique values and are more efficient for certain use cases.

Answer 5

A Symbol is a unique, immutable data type that can be used as a property key. It can be used to create object properties that can't be accessed using string keys.

Answer 6

Destructuring is a feature of JavaScript that allows you to extract values from arrays or objects into individual variables. It can be used to simplify code by making it more readable and less verbose.

Answer 7

A class is a blueprint for creating objects. Classes allow you to create objects with the same properties and methods and they can be used to define a contract that an object should follow.

Answer 8

The spread operator (...) allows you to expand an iterable (e.g. an array or a string) into its individual elements. It can be used to create a new array or to merge multiple arrays.

Answer 9

Async/Await is JavaScript keywords that allow you to write asynchronous code in a more synchronous-looking way, making it easier to read and understand. It allows you to write asynchronous code using synchronous code syntax.

Answer 10

The ternary operator is a shorthand way of writing an if-else statement in JavaScript. It can be used to test a condition and return a value based on the outcome.

Answer 11

Event bubbling is a mechanism that allows events to be propagated up the DOM tree. It happens when an event is triggered on a child element

Answer 12

Event capturing is a mechanism that allows events to be propagated down the DOM tree. It happens before the event reaches the target element and it can be used to track events at the top level of the DOM tree.

Answer 13

Event delegation is a technique where an event handler is attached to a parent element and it (the event handler) listens to the events on its child elements. It allows for avoiding adding event listeners to individual elements and reduces the number of event listeners that need to be managed.

Answer 14

The `bind()` method creates a new function that, when called, has its 'this' keyword set to the provided value, with a given sequence of arguments preceding any provided when the new function is called. It allows calling a function with a specific `this` value.

Answer 15

The `call()` method calls a function with a given `this` value and arguments provided individually. It allows calling a function with a specific `this` value and individual arguments.

Answer 16

The `apply()` method calls a function with a given `this` value and arguments provided as an array. It allows calling a function with a specific `this` value and an array of arguments.

Answer 17

A WeakMap is a collection of key-value pairs, similar to a Map, but its keys must be objects and the references to the keys are held weakly, allowing them to be garbage collected if there are no other references to them.

Answer 18

A WeakSet is a collection of unique values, similar to a Set, but the references to its values are held weakly, allowing them to be garbage collected if there are no other references to them.

Answer 19

Currying is a technique of breaking down a function that takes multiple arguments into a sequence of functions that each take a single argument. This can make the code more reusable and composable.

Answer 20

Recursion is a technique of calling a function from within itself until a certain condition is met. It can be useful for solving problems that can be broken down into smaller sub-problems.

Answer 21

A higher-order function is a function that takes one or more functions as arguments or returns a function as its result. It allows abstract functionality and writing more flexible and reusable code.

Answer 22

Composition is a technique of combining small, single-purpose functions to create more complex functionality. It allows for building more complex functionality by composing simple functions together.

Answer 23

Partial application is a technique of creating a new function by pre-filling some of the arguments of an existing function. It allows the creation of specialized versions of a function that are tailored to specific use cases.

Answer 24

Transpilation is the process of converting code written in one programming language to another, often to a more compatible version. It allows using modern language features even in environments that don't support them.

Answer 25

A Proxy is an object that acts as an intermediary between a target object and the code that interacts with it. It allows one to intercept and manipulate the behavior of an object.

Answer 26

Reflect API is a built-in object that provides a way to interact with objects in a more reflective way. It allows us to perform the same operations as the usual Object methods, but it also has some additional methods and it throws exceptions when the methods fail.

Important Concepts Flashcards

(50 cards)