jbmilgrom

const profiles = [
  {
    lastName: "Curry",
    firstName: "Steph",
    team: "WARRIORS"
  },
  {
    lastName: "James",
    firstName: "Lebron",
    team: "LAKERS",

jbmilgrom

enum PrimaryColor {
  Red = "RED",
  Yellow = "YELLOW",
  Blue = "BLUE"
}

const green = [
  { color: PrimaryColor.Yellow, weight: 1 / 2 },
  { color: PrimaryColor.Blue, weight: 1 / 2 }
] as const;

jbmilgrom

const HOURS_IN_DAY = 24;

/**
 * NOT VALID; imagined API for mutating numbers
 */
24.increment();

HOURS_IN_DAY === 25; // true

jbmilgrom

const oneHundred = 100; // <-- now a `const` instead of a `let`
const decrementOneHundred = x => oneHundred - x;

decrementOneHundred(20); // 80
// oneHundred = 80; <-- would be runtime error: "TypeError: Assignment to constant variable."
decrementOneHundred(20); // 80

jbmilgrom

const square = x => x * x;
const sum = (x, y) => x + y;

const sumOfSquares = (x, y, z) => sum(sum(square(x), square(y)), square(z));

sumOfSquares(1, 2, 3); // 14

jbmilgrom

const square = x => x * x;
const sum = (x, y) => x + y;

// PSUEDO CODE
sum(sum(square(USER_INPUT_1), square(USER_INPUT_2)), square(USER_INPUT_3));

// REPL PSUEDO CODE
// > run functionalProgram.js with USER_INPUT_1=1, USER_INPUT_2=2, USER_INPUT_3=3,
// > 14

jbmilgrom

class BankAccount {
    public balance; // <-- now public

    constructor(funds) {
        this.balance = funds;
    }

    public withdraw(amount) {
        this.balance = this.balance - amount;
    }

jbmilgrom

class BankAccount {
    public withdraw(balance, amount) {
        return balance - amount;
    }

    public checkBalance(balance) {
        return balance;
    }
}

jbmilgrom

function loginOrReloadAndGetPage(page: BasePage, username, password) {
  page.load();
  ...
  page.waitForInitLoaded();
  ...
  if (!page.isLoggedIn()) {
    ...
    page.waitForInitLoaded();
  }
  return page.waitForLoaded();

jbmilgrom

class BuyingFlow extends BasePage {
  ...
}

class BuyingFlow implements BasePageI {
  load() {}
  waitForInitloaded() {}
}

const BuyingFlow: BasePageI = {