Introduction to JavaScript

Key Questions Answered

• What is JavaScript?

  • Popular programming language.
  • Used by companies like Netflix, Walmart, and PayPal.
  • Average salary of a JavaScript developer in the US is $72,000.
  • Opportunities in front-end, back-end, and full-stack development.

• What can you do with JavaScript?

  • Originally for building interactive web pages in browsers.
  • Now used for full-blown web/mobile apps, real-time apps (chat, video streaming), command-line tools, and games.

• Where does JavaScript run?

  • In browsers with a JavaScript engine (e.g., SpiderMonkey in Firefox, V8 in Chrome).
  • Outside browsers using Node.js (created by embedding V8 in a C++ program).

• JavaScript vs. ECMAScript?

  • ECMAScript: Specification by ECMA.
  • JavaScript: Language conforming to ECMAScript.
  • ECMAScript 2015 (ES6) introduced new features.

Writing JavaScript Code

• Using Chrome Developer Tools

  • Right-click -> Inspect -> Console tab.
  • Can execute JavaScript directly.

• Setting up Development Environment

  • Recommended tools: Visual Studio Code and Node.
  • Create a folder and use VS Code for organizing code.
  • Use Live Server extension for serving web apps.

JavaScript Basics

Variables

• Use let to declare variables.
• Variables can store strings, numbers, booleans, undefined, and null values.
• Follow naming rules: meaningful, no reserved keywords, cannot start with numbers, no spaces or hyphens.

Constants

• Use const for values that should not change.

Data Types

• Primitives: Strings, numbers, booleans, undefined, null.
• Reference Types: Objects, arrays, functions.
• JavaScript is a dynamic language; types can change at runtime.

Objects

• Used to group related variables as properties.
• Access properties using dot notation or bracket notation.

Arrays

• Used for lists of items.
• Dynamic in size and content type.
• Access elements by index.

Functions

• Set of statements performing a task or calculating a value.
• Can take inputs (parameters) and return outputs.
• Function declarations use function keyword.

Advanced Usage

• Functions can perform tasks or return values.
• Arrays and objects enhance organization and manipulation of data.
• Encouraged to explore further courses for in-depth learning.