Unit 8: Core JavaScript Concepts & Functions

8.1 JavaScript Basics & Data Types

JavaScript & ES6:

• ECMAScript (ES6) - Modern JavaScript standard
• JavaScript runs in browsers and Node.js

Variables (var, let, const):

• var: Function-scoped, can be re-declared
• let: Block-scoped, cannot be re-declared
• const: Block-scoped, cannot be re-assigned

Data Types:

• Number, String, Boolean, Null, Undefined, Symbol, Object
• Arrays: [1, 2, 3] or new Array()
• Objects: {name: "John", age: 25}

Template Literals (ES6):

• Use backticks: `Hello ${name}`
• Allows multi-line strings and interpolation

Array Methods:

• push() - Add element at end
• pop() - Remove last element
• map() - Transform each element
• filter() - Create array of filtered elements
• forEach() - Loop through array
• includes() - Check if element exists
• find() - Find first matching element

8.2 Loops, Conditions & Functions

Loops:

• for, while, do...while
• for...of - Iterate over values
• for...in - Iterate over keys/indexes

Conditions:

• if...else, else if
• switch...case...default
• Ternary operator: condition ? true : false

Functions:

• Declaration: function myFunc() { }
• Expression: const myFunc = function() { }
• Arrow Function (ES6): const myFunc = () => { }
• Parameters and return values
• Default Parameters: function(a = 5, b = 10) { }
• Rest Parameter: ...args collects multiple arguments into array
• Spread Operator: ...array spreads array elements

8.3 Popup Boxes

JavaScript Popup Methods:

• alert() - Show message and OK button
• confirm() - Show message with OK/Cancel (returns boolean)
• prompt() - Ask user for input (returns string or null)