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Overview of JavaScript Programming

Apr 28, 2025

Introduction to JavaScript

Frequently Asked Questions

  1. What is JavaScript?

    • One of the most popular programming languages in the world.
    • Used by companies like Netflix, Walmart, and PayPal.
    • Average salary for a JavaScript developer in the US is $72,000/year.
    • Opportunities as front-end, back-end, or full stack developer.
  2. What can you do with JavaScript?

    • Originally used for building interactive web pages.
    • Now used for building full-blown web/mobile apps, real-time networking apps, command-line tools, and games.
  3. Where does JavaScript code run?

    • Initially designed to run in browsers (JavaScript engines like SpiderMonkey for Firefox and V8 for Chrome).
    • Node.js allows JavaScript to run outside browsers on servers.
  4. Difference between JavaScript and ECMAScript?

    • ECMAScript is a specification; JavaScript conforms to this specification.
    • ECMAScript standards are maintained by ECMA International.
    • ES6 (released in 2015) introduced many new features.

Writing and Running JavaScript

  • JavaScript can be executed in browser consoles or in Node.js.
  • Recommended development setup includes Visual Studio Code and Node.js.
  • HTML and JavaScript Interaction:
    • Use script tags to run JavaScript in HTML.
    • Script should be placed at the end of body tag for better performance.

Development Tools

  • Code Editors:
    • Visual Studio Code, Sublime Text, Atom.
  • Node.js:
    • Useful for executing JavaScript outside the browser.

JavaScript Basics

Variables

  • Used to store data temporarily.
  • Declared using let (for mutable) and const (for immutable).
  • Must have meaningful names, cannot start with numbers, use camelCase.

Primitive Types

  • Strings, Numbers, Booleans, Undefined, Null.
  • JavaScript is a dynamic language; types can change at runtime.

Objects

  • Used to group related variables.
  • Created using object literals with key-value pairs.
  • Access properties using dot or bracket notation.

Arrays

  • Data structures to store lists of items.
  • Length and type of items can change dynamically.
  • Arrays are objects in JavaScript.

Functions

  • Blocks of code that perform tasks or calculate values.
  • Can have parameters (inputs) and return values.
  • Functions can be reused with different arguments.

Additional Concepts

  • Dynamic Typing:
    • Type of a variable can change based on the assigned value.
  • Type Checking:
    • Use typeof to check variable type.

Summary

  • JavaScript enables creating a wide range of applications from web pages to server-side apps.
  • Understanding variables, data types, objects, arrays, and functions is crucial for JavaScript programming.
  • Tools like Node.js and VS Code enhance development and execution of JavaScript applications.