JavaScript ES6 Features Quiz

ES6 Features

• Let and Const:

  • let allows block-scoped variable declaration.
  • const is used for constants, also block-scoped.

• Arrow Functions:

  • Shorter syntax for functions (e.g., const add = (a, b) => a + b;).
  • Lexical this binding, which retains the context of this.

• Template Literals:

  • String interpolation with backticks (`Hello ${name}`).
  • Multiline strings without concatenation.

• Destructuring Assignment:

  • Extract values from arrays or properties from objects (e.g., const {a, b} = obj;).

• 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) {}).

• Classes:

  • Syntax for creating objects and inheritance (e.g., class Dog extends Animal {}).

• Modules:

  • Support for modular code using import and export.

DOM Manipulation

• Selecting Elements:

  • document.getElementById(), document.querySelector(), document.querySelectorAll().

• Modifying Elements:

  • Change content: element.textContent, element.innerHTML.
  • Change styles: element.style.property.

• Creating and Removing Elements:

  • Create: document.createElement().
  • Append: parentElement.appendChild(childElement).
  • Remove: parentElement.removeChild(childElement).

• 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 async function to wrap code and await to 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.

• 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).

• Event Delegation:

  • Attach a single event listener to a parent element to manage events for multiple child elements.

ES6 Features

• Let and Const:

  • let enables block-level variable scoping, allowing variables to be limited to the block, statement, or expression where they are defined.
  • const declares 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.

• Template Literals:

  • Allow for easy string interpolation using backticks (`Hello ${name}`).
  • Enable multiline strings without the need for concatenation, enhancing readability.

• Destructuring Assignment:

  • Facilitates unpacking values from arrays and properties from objects in a more intuitive way (e.g., const {a, b} = obj;).

• 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) {}).

• Classes:

  • Introduce a cleaner syntax for creating objects and handling inheritance (e.g., class Dog extends Animal {}).

• Modules:

  • Support the modular structure of code through import and export statements, promoting reusable components.

DOM Manipulation

• Selecting Elements:

  • Use methods like document.getElementById(), document.querySelector(), and document.querySelectorAll() to access DOM elements effectively.

• Modifying Elements:

  • Change the content of elements directly using element.textContent or element.innerHTML.
  • Modify styles dynamically via element.style.property.

• Creating and Removing Elements:

  • Create new elements with document.createElement(), allowing for dynamic content generation.
  • Append or remove elements using parentElement.appendChild(childElement) or parentElement.removeChild(childElement).

• Event Listeners:

  • Attach event handlers using element.addEventListener(event, handler) to respond to user interactions.

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 async function to wrap code and use await to 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.

• 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.

• 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.