Basics

const leet = 1337;
const yummy = 3.14;
const loss = -1000;

console.log(1337 === 1337.00); // true

{ 
  let million = 1_000_000;
  console.log(million === 1000000); // true
}

{ 
  let million = 1e6;
  console.log(million === 1000000); // true
}

console.log(1e-6 === 0.000001); // true

console.log(typeof leet); // 'number'

console.log(.1 + .2); // 0.30000000000000004 - https://0.30000000000000004.com/

Mathematical Operators

// addition
console.log(1 + 1); // 2

// subtraction
console.log(5 - 1); // 4

// multiplication
console.log(5 * 2); // 10

// division
console.log(10 / 4); // 2.5

// remainder
console.log(3 % 2); // 1 
console.log(6 % 3); // 0

// exponent
console.log(2 ** 3); // 8

Shorthand Assignment

{
  let addition = 123;
  addition = addition + 1;
  console.log(addition); // 124
}

let addition = 123;
addition += 1;
console.log(addition); // 124

let subtraction = 123;
subtraction -= 55;
console.log(subtraction); // 68

let multiplication = 123;
multiplication *= 2;
console.log(multiplication); // 246

let division = 123;
division /= 2;
console.log(division); // 61.5

let remainder = 5;
remainder %= 2;
console.log(remainder); // 1

let exponent = 16;
exponent **= .5;
console.log(exponent); // 4

Unary Operators

Addition and Subtraction

{
  let example = 0;
  example++;
  console.log(example); // 1
  ++example;
  console.log(example); // 2
}

{
  let example = 0;
  example--;
  console.log(example); // -1
  --example;
  console.log(example); // -2
}

Pre vs Post

{
  let example = 0;
  let result = example++;
  console.log(result); // 0
  console.log(example); // 1
}
{
  let example = 0;
  let result = ++example;
  console.log(result); // 1
  console.log(example); // 1
}

{
  let example = 0;
  let result = example--;
  console.log(result); // 0
  console.log(example); // -1
}
{
  let example = 0;
  let result = --example;
  console.log(result); // -1
  console.log(example); // -1
}

Comparison Operators

// less than
console.log(1 < 3); // true 

// greater than
console.log(1 > 3); // false

// less than or equal
console.log(3 <= 3); // true 

// greater than or equal
console.log(4 >= 5); // false

// greater than or equal
console.log(4 >= 5); // false

// strict equality
console.log(1 === 1); // true

// strict inequality
console.log(5 !== 3); // true

Integral Limits

console.log(Number.MAX_SAFE_INTEGER); // 9007199254740991
console.log(Number.MIN_SAFE_INTEGER); // -9007199254740991

console.log(Number.MAX_SAFE_INTEGER + 1);  // 9007199254740992 - Correct (but ambiguous)
console.log(Number.MAX_SAFE_INTEGER + 2);  // 9007199254740992 - Rounded!

// Safe value
console.log(Number.isSafeInteger(Number.MAX_SAFE_INTEGER)); // true

// Unsafe values (it might have been rounded to it due to overflow)
console.log(Number.isSafeInteger(Number.MAX_SAFE_INTEGER + 1)); // false
console.log(Number.isSafeInteger(9007199254740999)); // false

Infinity

console.log(10 ** 1000); // Infinity
console.log(-1 * 10 ** 1000); // -Infinity

console.log(1 / 0); // Infinity
console.log(-1 / 0); // -Infinity

console.log(Infinity === Infinity); // true
console.log(-Infinity === -Infinity); // true

console.log(Infinity > 1); // true
console.log(-Infinity < -1); // true

console.log(Number.POSITIVE_INFINITY === Infinity);  // true
console.log(Number.NEGATIVE_INFINITY === -Infinity); // true

String Interop

const meaningOfLife = 42;
console.log(meaningOfLife.toString()); // '42'

const message = 'The meaning of life is: ' + 42;
console.log(message); // 'The meaning of life is: 42'

const change = 123.353;
console.log(change.toString()); // '123.353'
console.log(change.toFixed(2)); // '123.35' - rounded down
console.log(change.toFixed(1)); // '123.4' - rounded up

console.log(meaningOfLife.toFixed(2)); // '42.00'

String Parsing

const meaningOfLife = '42';

console.log(parseInt(meaningOfLife)); // 42

const change = '23.55';

console.log(parseInt(change)); // 23
console.log(parseFloat(change)); // 23.55
console.log(+change); // 23.55

NaN

const powerPuff = 'Sugar, spice and everything nice';

const valueOfPower = parseInt(powerPuff);
console.log(valueOfPower); // NaN

console.log(0 / 0); // NaN

const first = parseFloat('Alpha'); // NaN
const second = parseFloat('Beta'); // NaN

console.log(first !== second); // true

console.log(NaN !== NaN); // true
console.log(NaN === NaN); // false

console.log(first === NaN); // false

console.log(isNaN(NaN)); // true
console.log(isNaN(first)); // true

Number Bases

const perfect = 2 ** 5;

console.log(perfect == 32); // true
console.log(perfect === 0b100000); // true
console.log(perfect === 0o40); // true
console.log(perfect === 0x20); // true

// case insensitive
console.log(0b0 === 0B0); // true
console.log(0o0 === 0O0); // true
console.log(0x0 === 0X0); // true

console.log(perfect.toString()); // '32'
console.log(perfect.toString(2)); // '100000'
console.log(perfect.toString(8)); // '40'
console.log(perfect.toString(16)); // '20'

console.log(parseInt('32')); // 32
console.log(parseInt('100000', 2)); // 32
console.log(parseInt('40', 8)); // 32
console.log(parseInt('20', 16)); // 32

Math Built-in Module

console.log(Math.floor(1.99)); // 1
console.log(Math.ceil(1.01)); // 2

console.log(Math.round(1.99)); // 2
console.log(Math.round(1.01)); // 1
console.log(Math.round(1.5)); // 2

Math.random(); // a random floating point in the range (>=0 && <1)

const coinToss = Math.floor(Math.random() * 2); // 0 or 1
const diceRoll = Math.floor(Math.random() * 6); // 0, 1, 2, 3, 4, or 5

console.log(Math.max(1, 2, 3)); // 3
console.log(Math.min(1, 2, 3)); // 1

function calculateCircumference(radius) {
  return 2 * Math.PI * radius;
}
console.log(calculateCircumference(1)); // 6.283185307179586

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Basics

Mathematical Operators

Shorthand Assignment

Unary Operators

Addition and Subtraction

Pre vs Post

Comparison Operators

Integral Limits

Infinity

String Interop

String Parsing

NaN

Number Bases

Math Built-in Module

Transcript

Professional Modern JavaScript