basics.js

developer tools > console
4 + 5
9 * 2
12 / 4
2 ** 3
true && false
true || false

age = 19
name = "Hasssan"
message = "Hello I am " + name
hisAge = 14
difference = age - hisAge
message = name + " is " + difference + " years older than him"

number1 = 7
number2 = 8
number3 = number1 * number2
number1 > number2
number3 == number1

check1 = number1 < number2
check2 = number2 >= number3
check3 = check1 || check2


window.addEventListener('load', function() {

	// log to the console
	console.log("Hello console from script.js")
	
	// write in HTML document
	document.write("<h1>This is a heading</h1>")
	document.write("<p>a long long paragaph</p>")
	
  // Using tempelate string to write to multiple lines
	fewMoreLines = `
		<h1>HEADING 1</h1>
		<h2>HEADING 2</h2>
		<h3>HEADING 3</h3>
	`
	document.write(fewMoreLines)
	
	// Data types
	string = '4'
	number = 4
  boolean = true // or false
	console.log(str + number)
	console.log(str == number) // type conversion
	console.log(str === number)
	
	// Math Functions
	let a = 25
	let b = 49
	let max = Math.max(a,b)
	let min = Math.min(a,b)
	let squareRootOfA = Math.sqrt(a)
	let aSquared = Math.pow(a, 2)
	
	console.log(a, b)
	console.log(max, min)
	console.log(squareRootOfA)
	console.log(aSquared)

	// User Input (alert box)
	let name = prompt("What is your name?")
	document.write("<h1>"+ name +"</h1>")
	document.write(`<h1>${name}</h1>`)
	
  // User Input is read as a string
	let number = prompt("Enter a number to be doubled")
	let numberDoubled = number + number // Will concatenate
	alert(numberDoubled)
  
  // You need to use parseInt(str) convert the type
  let str = prompt("Enter a number to be doubled")
  let number = parseInt(str)
	let numberDoubled = number + number // Addition
	alert(numberDoubled)
	
	// Strings
	let str = "This is some string"
	console.log(str.length)
	console.log(str.charAt(1)) // "h"
	console.log(str.toLowerCase())
	console.log(str.toUpperCase())
})