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Video Lesson

Lesson Notes

null vs undefined

In JavaScript, undefined means a variable has been declared but not given a value, whereas null is an assignment value that represents “no value.”

// undefined example
let x;
console.log(x); // undefined

// null example
let y = null;
console.log(y); // null

When to use:

Use undefined to signify an uninitialized variable or missing function arguments.
Use null to explicitly indicate that a variable should have no value.

Key Points:

typeof undefined returns "undefined".
typeof null returns "object" (a known JavaScript quirk).
Both null == undefined is true, but null === undefined is false.

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Primitives in Javascript

Equality Operators in JavaScript

Javascript "null" vs "undefined"

In JavaScript, undefined means a variable has been declared but not given a value, whereas null is an assignment value that represents “no value.”

3m 20s

Course Content

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1. Introduction & Setup

0 of 4 completed

Setting up VS Code

Creating Your First HTML Page with VS Code and AI

Creating and Linking Your First JavaScript File in VS Code

Understanding the Basic HTML Structure for JavaScript Integration

2. Variables, Data Types, Operators

0 of 9 completed

Variables using the "var" keyword

Variables with "const" and "let" keywords

Code comments

String Interpolation (Template Literals)

Block Scope

Primitives in Javascript

Javascript "null" vs "undefined"

Equality Operators in JavaScript

Greater Than and Less Than in JavaScript

3. Control Structures ("If", "Else" statements and loops)

0 of 7 completed

Conditional Logic: `if`, `else if`, and `else`

Switch Statements

Basic For Loop

While Loop: Basics

`do...while` Loop Explained

Nested Loops in JavaScript

`break` and `continue` in JavaScript Loops

4. Arrays, Objects and Iterables

0 of 7 completed

Basic Arrays in Javascript

Exploring Array Properties

Array Indexing, Access Elements

Array Iteration with JavaScript For Loops

Array Iteration: Using `for...of` in JavaScript

Basic Objects in JavaScript (Simple)

Basic This

5. Functions

0 of 5 completed

Basic functions

Return values from functions

Function Expressions

Arrow functions

"this" keyword in arrow functions

6. Promises, Async and Await

0 of 0 completed

7. The DOM

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