JavaScript Cheat Sheets

// => Hello world! console.log("Hello world!"); // => Hello CheatSheets.zip console.warn("hello %s", "CheatSheets.zip"); // Output error message to standard error console.error(new Error("Oops!"));

let amount = 6; let price = 4.99;

let x = null; let name = "Tammy"; const found = false; // => Tammy, false, null console.log(name, found, x); var a; console.log(a); // => undefined

let single = "Wheres my bandit hat?"; let double = "Wheres my bandit hat?"; // => 21 console.log(single.length);

5 + 5 = 10 // Addition 10 - 5 = 5 // Subtraction 5 * 10 = 50 // Multiplication 10 / 5 = 2 // Division 10 % 5 = 0 // Modulus

// This is a comment /* You need to change this setting before deployment. */

let number = 100; // Both statements add 10 number = number + 10; number += 10; console.log(number); // => 120

let age = 7; // String concatenation "Tommy is " + age + " years old."; // String interpolation `Tommy is ${age} years old.`;

const isMailSent = true; if (isMailSent) { console.log("Mail sent to recipient"); }

var x = 1; // => true result = x == 1 ? true : false;

true || false; // true 10 > 5 || 10 > 20; // true false || false; // false 10 > 100 || 10 > 20; // false

1 > 3; // false 3 > 1; // true 250 >= 250; // true 1 === 1; // true 1 === 2; // false 1 === "1"; // false

const fruits = ["apple", "orange", "banana"]; // Different data types const data = [1, "chicken", false];

const apple = { color: "Green", price: { bulk: "$3/kg", smallQty: "$4/kg" }, }; console.log(apple.color); // => Green console.log(apple.price.bulk); // => $3/kg

class Dog { constructor(name) { this._name = name; } introduce() { console.log("This is " + this._name + " !"); } // Static method static bark() { console.log("Woof!"); } } const myDog = new Dog("Buster"); myDog.introduce(); // Calling static method Dog.bark();

// myMath.js // Default export export default function add(x, y) { return x + y; } // Named export export function subtract(x, y) { return x - y; } // Multiple exports function multiply(x, y) { return x * y; } function duplicate(x) { return x * 2; } export { multiply, duplicate };

function helloWorld() { return new Promise((resolve) => { setTimeout(() => { resolve("Hello World!"); }, 2000); }); } async function msg() { const msg = await helloWorld(); console.log("Message:", msg); } msg(); // Message: Hello World! <-- after 2 seconds