Syntax Station

let myInt = 101;                 // Number (Integer)
let myFloat = 45.81;             // Number (Float)
let positive = true;             // Boolean
let message = "Hello World!";    // String
const PI = 3.14159;              // Constant

let letter;     // Declaration
letter = 'a';   // Initialization

// Comment on a single line
/*
   Block comments
   Everything in here will be
   treated as a comment
*/

let foo = 5;
foo++;

let bar = 10;
foo = foo + bar;

/*
     + : Addition             - : Subtraction
     * : Multiplication       / : Division
     % : Modulus Division

     ++ : Increase by 1       -- : Decrease by 1
*/

foo += 12;   // Addition assignment operator
foo -= 35;   // Subtraction assignment operator

let year = 2018;

if (year > 2018) {
   message = "After 2018";
}
else if (year < 2018) {
   message = "Before 2018";
}
else {
   message = "The year is 2018!";
}

/*
   ==  : Equal to (loose)      !=  : Not Equal to
   === : Equal to (strict)     !== : Not Equal to (strict)
   >   : Greater than          <   : Less than
   >=  : Greater or equal      <=  : Less or equal
*/

let foo = 0;

// While Loop
while (foo < 100) {
   foo++;
}

let sum = 0;

// For Loop
for (let i = 0; i < 100; i++) {
   sum += i;   // adds all values from 0 to 99
}

// Declares an array "points"
let points = [];

points[0] = 716;
points[1] = 482;
console.log(points[1]);   // Prints 482

// Initialize at declaration
let grades = ['A', 'C', 'A', 'B'];

// Array length
let count = grades.length;

function isNegative(n) {
   return n < 0;
}

let answer = isNegative(-5);
if (answer) {
   console.log("Number is negative!");
}

// Arrow Function
const add = (a, b) => a + b;

let person = {
    name: "Bob",
    age: 30,
    ssn: 123456789
};

// Access properties
console.log(person.name); // Prints "Bob"
console.log(person["age"]); // Prints 30

// Classes (ES6+)
class Car {
    constructor(brand) {
        this.carname = brand;
    }
}
let myCar = new Car("Ford");