Questions and Answers
What functionality allows you to use event delegation in JavaScript?
Which feature is NOT a characteristic of Angular?
What does the event.preventDefault() method accomplish in event handling?
Which statement accurately describes Node.js?
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What distinguishes Vue.js from other frameworks like Angular and React?
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In event handling, which term describes how events flow from child to parent elements?
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What is the primary purpose of using const in JavaScript?
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Which of the following correctly utilizes the spread operator?
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Which method allows you to modify an element's styling in the DOM?
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How does the async/await syntax improve asynchronous programming?
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What is the main function of an event listener in JavaScript?
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Which of the following statements is true regarding template literals?
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In the context of ES6 classes, what does the extends keyword accomplish?
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What does the Promise.all() method do?
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Study Notes
ES6 Features
-
Let and Const:
-
letallows block-scoped variable declaration. -
constis used for constants, also block-scoped.
-
-
Arrow Functions:
- Shorter syntax for functions (e.g.,
const add = (a, b) => a + b;). - Lexical
thisbinding, which retains the context ofthis.
- Shorter syntax for functions (e.g.,
-
Template Literals:
- String interpolation with backticks (
`Hello ${name}`). - Multiline strings without concatenation.
- String interpolation with backticks (
-
Destructuring Assignment:
- Extract values from arrays or properties from objects (e.g.,
const {a, b} = obj;).
- Extract values from arrays or properties from objects (e.g.,
-
Spread and Rest Operators:
- Spread:
...expands an iterable (e.g.,const arr = [1, 2, ...otherArr];). - Rest:
...collects arguments into an array (e.g.,function sum(...args) {}).
- Spread:
-
Classes:
- Syntax for creating objects and inheritance (e.g.,
class Dog extends Animal {}).
- Syntax for creating objects and inheritance (e.g.,
-
Modules:
- Support for modular code using
importandexport.
- Support for modular code using
DOM Manipulation
-
Selecting Elements:
-
document.getElementById(),document.querySelector(),document.querySelectorAll().
-
-
Modifying Elements:
- Change content:
element.textContent,element.innerHTML. - Change styles:
element.style.property.
- Change content:
-
Creating and Removing Elements:
- Create:
document.createElement(). - Append:
parentElement.appendChild(childElement). - Remove:
parentElement.removeChild(childElement).
- Create:
-
Event Listeners:
-
element.addEventListener(event, handler)for handling events.
-
Async Programming
-
Callbacks: Functions passed as arguments to handle asynchronous operations.
-
Promises:
- Objects representing the eventual completion (or failure) of an asynchronous operation.
- Methods:
.then(),.catch(),.finally().
-
Async/Await:
- Syntactic sugar over promises for cleaner asynchronous code.
- Use
asyncfunction to wrap code andawaitto pause execution until promise resolves.
JavaScript Frameworks
-
React:
- Component-based architecture for building user interfaces.
- Utilizes a virtual DOM for optimized rendering.
-
Angular:
- Full-fledged framework for building web applications with TypeScript.
- Features two-way data binding and dependency injection.
-
Vue.js:
- Progressive framework for building user interfaces.
- Combines features from React and Angular for flexibility.
-
Node.js:
- Runtime environment that allows JavaScript to be run on the server side.
- Uses an event-driven, non-blocking I/O model.
Event Handling
-
Event Types:
- Click, mouseover, keypress, etc.
-
Adding Event Handlers:
- Use
addEventListener()to attach functions to events.
- Use
-
Event Propagation:
- Bubbling: Events bubble up from child to parent elements.
- Capturing: Events capture down from parent to child elements.
-
Prevent Default Behavior:
- Use
event.preventDefault()to prevent default action (e.g., preventing form submission).
- Use
-
Event Delegation:
- Attach a single event listener to a parent element to manage events for multiple child elements.
ES6 Features
-
Let and Const:
-
letenables block-level variable scoping, allowing variables to be limited to the block, statement, or expression where they are defined. -
constdeclares block-scoped constants that cannot be reassigned after their initial value.
-
-
Arrow Functions:
- Provide a concise syntax for function expressions (e.g.,
const add = (a, b) => a + b;). - Maintain the lexical context of
this, making them particularly useful for callbacks and methods.
- Provide a concise syntax for function expressions (e.g.,
-
Template Literals:
- Allow for easy string interpolation using backticks (
`Hello ${name}`). - Enable multiline strings without the need for concatenation, enhancing readability.
- Allow for easy string interpolation using backticks (
-
Destructuring Assignment:
- Facilitates unpacking values from arrays and properties from objects in a more intuitive way (e.g.,
const {a, b} = obj;).
- Facilitates unpacking values from arrays and properties from objects in a more intuitive way (e.g.,
-
Spread and Rest Operators:
- Spread operator (
...) allows the expansion of iterable elements into a new array or argument list (e.g.,const arr = [1, 2,...otherArr];). - Rest operator (
...) collects multiple arguments into an array for easier handling in functions (e.g.,function sum(...args) {}).
- Spread operator (
-
Classes:
- Introduce a cleaner syntax for creating objects and handling inheritance (e.g.,
class Dog extends Animal {}).
- Introduce a cleaner syntax for creating objects and handling inheritance (e.g.,
-
Modules:
- Support the modular structure of code through
importandexportstatements, promoting reusable components.
- Support the modular structure of code through
DOM Manipulation
-
Selecting Elements:
- Use methods like
document.getElementById(),document.querySelector(), anddocument.querySelectorAll()to access DOM elements effectively.
- Use methods like
-
Modifying Elements:
- Change the content of elements directly using
element.textContentorelement.innerHTML. - Modify styles dynamically via
element.style.property.
- Change the content of elements directly using
-
Creating and Removing Elements:
- Create new elements with
document.createElement(), allowing for dynamic content generation. - Append or remove elements using
parentElement.appendChild(childElement)orparentElement.removeChild(childElement).
- Create new elements with
-
Event Listeners:
- Attach event handlers using
element.addEventListener(event, handler)to respond to user interactions.
- Attach event handlers using
Async Programming
-
Callbacks:
- Functions that are passed as arguments and are executed after a particular event or completion of a task, commonly used for asynchronous operations.
-
Promises:
- Represent the eventual completion (or failure) of an asynchronous operation, providing a more manageable way to handle asynchronous code.
- Support methods such as
.then(),.catch(), and.finally()for streamlined success/failure handling.
-
Async/Await:
- Syntactical sugar built on top of promises, allowing for simpler writing of asynchronous code.
- Define an
asyncfunction to wrap code and useawaitto pause execution until the promise settles.
JavaScript Frameworks
-
React:
- A component-based library designed for building user interfaces with a focus on a virtual DOM to enhance performance.
-
Angular:
- A comprehensive framework leveraging TypeScript, featuring robust architecture with support for two-way data binding and dependency injection.
-
Vue.js:
- A progressive JavaScript framework combining features from both React and Angular, providing flexibility in UI development.
-
Node.js:
- A server-side runtime environment allowing JavaScript to run outside of the browser, driven by an event-driven, non-blocking I/O model.
Event Handling
-
Event Types:
- Various user interactions can trigger events, including click, mouseover, and keypress.
-
Adding Event Handlers:
- Use
addEventListener()to link specific functions to events, enhancing interactivity.
- Use
-
Event Propagation:
- Bubbling: Events propagate from child elements to parent elements.
- Capturing: Events capture from parent elements to child elements before reaching the target.
-
Prevent Default Behavior:
- Use
event.preventDefault()to stop the default action associated with an event, such as form submissions.
- Use
-
Event Delegation:
- Attach a single event listener to a parent element to manage events for multiple child elements efficiently, optimizing performance and reducing memory usage.
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Description
Test your knowledge on the key features of ES6 in JavaScript. This quiz covers topics like let and const, arrow functions, template literals, and destructuring assignment. Enhance your understanding of modern JavaScript syntax and functions.
