Javascript

JavaScript Study Guide

What is JavaScript?

• A high-level, dynamic, untyped, and interpreted programming language.

• Primarily known for making web pages interactive.

Basic Concepts:

1. Variables: Storing information for reuse.

   • Declared using var, let, or const.

     • Example: let name = 'John';

2. Data Types:

   • String: Textual data (e.g., 'Hello World')

   • Number: Numerical data (e.g., 42)

   • Boolean: True or false (e.g., true)

   • Object: Collection of key-value pairs (e.g., {key: 'value'})

   • Array: List-like object (e.g., [1, 2, 3])

3. Operators:

   • Arithmetic: +, -, *, /

   • Assignment: =, +=, -=

   • Comparison: ==, ===, !=, !==, >, <

4. Control Structures:

   • Conditional Statements: if, else if, else

   • Loops: for, while, do while

     • Example: for(let i = 0; i < 5; i++) { console.log(i); }

5. Functions:

   • Blocks of code designed to perform a particular task.

   • Declared using the function keyword.

     • Example: function greet() { console.log('Hello!'); }

Manipulating the DOM:

• JavaScript can access and manipulate HTML and CSS.

• Use document.getElementById(), document.querySelector(), etc.

Events:

• JavaScript can respond to user actions, such as clicks or key presses.

• Example: button.addEventListener('click', function() { alert('Button clicked!'); });

Best Practices:

• Keep code organized and easy to read.

• Use descriptive variable and function names.

• Comment your code for clarity.

Resources for Further Learning:

• Mozilla Developer Network (MDN)

• FreeCodeCamp

• Codecademy