JS

Why JS? 😕

I love that 😍

Learning path 🗺

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1. Introduction

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2. Control flow

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3. Functions

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4. Arrays

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5. Objects

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6. DOM

Primitives

// 1) Numbers
4
8.5
-3

// 2) Strings
"Hello, World!"
"815334455292"

// 3) Booleans
true
false

// 4) null
null

// 5) undefined
undefined

💪🏻

// .1
200 % 3

// 2.
("Hello, " + "World!")[6]

// 3.
"hello".length % "world".length

Variables 📦

Variables are containers that store values

2 choices ✌🏻

1. Do you have values that you don't want changed or that will never change? Like the value of mathematical pi, they can be assigned to const in javascript.

2. With let, we can re-assign the value.

null & undefined 😬

They will discuss later

console.log

alert

promp

<!DOCTYPE html>
<html>
	<head>...</head>
	<body>
    ...
    <script>
    	console.log('Give me pizza 🍕');
    <script>
	</body>
</html>

Code JS in a Separate File

console.log('Give me pizza 🍕');

index.html

pizza.js

<!DOCTYPE html>
<html>
	<head>...</head>
	<body>
    	...
    	<script src="./pizza.js"></script>
	</body>
</html>

Greet Exercise 👋

Ask user's first name
Ask user's last name
Say Hello by calling user's full name

Ask user's first name
Ask user's last name
Say Hello by calling user's full name

Pizza Exercise 🍕

Ask user's budget
Say How many pizzas can a user buy?

Boolean Logic

Operator	Name	Example	Result
>	Greater than	x > 10	false
>=	Greater than or equal to	x >= 5	true
<	Less than	x < -50	false
<=	Less than or equal to	x <= 100	true
==	Equal to	x == "5"	true
!=	Not equal to	x != "b"	true
===	Equal value and type	x === "5"	false
!==	Not equal value or equal type	x !== "5"	true

Comparison Operators

x = 5

Logical Operators

AND, OR, and NOT

Operator	Name	Example	Result
&&	AND	x < 10 && x !== 5	false
\|\|	OR	y > 9 \|\| x === 5	true
!	NOT	!(x === y)	true

Exercise 1

const x = 10;
const y = "a"

y === "b" || x >= 10

Exercise 2

const x = 3;
const y = 8;

!(x == "3" || x === y) && !(y != 8 && x <= y)

Truthy and Falsy

Values that aren't actually true or false, are still inherently "truthy" or "falsey" when evaluated in a boolean context

!"Hello World"

!""

!null

!0

!-1

!NaN

JS

By Ali Montajebi

JS