halan

const add = (a, b) => a + b;

add.length // 2

const add10 = add.bind(this, 10);

add10.length // 1

console.log(add10(5)); // 15

halan

let accumulator = 0;

for(let index = 0; index < collection.length; index++) {
  accumulator = // get current accumulator and collection[index] and do some calculation
}
  
return accumlator;

halan

const totalLine = line =>
  line.quantity * line.price;

const sum = (a, b) => a + b;

const map = fn => xs => xs.map(fn);

const reduce = (fn, ini) => xs => xs.reduce(fn, ini)

const sumTotal = lines =>

halan

const totalLine = line =>
  line.quantity * line.price;

const sum = (a, b) => a + b;

const sumTotal = lines =>
  lines.map(totalLine).reduce(sum, 0);

console.log(sumTotal(lineItems));

halan

const lineItems = [
  { name: 'Carmenere', price: 35, quantity: 2 },
  { name: 'Cabernet', price: 50, quantity: 1 },
  { name: 'Merlot', price: 98, quantity: 10 },
];

const totalLine = line =>
  line.quantity * line.price;

const sumTotal = lines =>

halan

const totalLine = line => line.quantity * line.price;

const sumTotal = lines => {
  let total = 0;
  
  for(let i = 0; i < lines.length; i++) {
    total += totalLine(lines[i])
  }
  
  return total;

halan

const lineItems = [
  { name: 'Carmenere', price: 35, quantity: 2 },
  { name: 'Cabernet', price: 50, quantity: 1 },
  { name: 'Merlot', price: 98, quantity: 10 },
];


const sumTotal = lines => {
  let total = 0;
  

halan

import { createStore } from 'redux'

const Pokemon = {
  init: (specie) => ({ level: 1, specie }),
  setSpecie: (prev, specie) => ({ ...prev, specie }),
  updateLevel: (prev) => ({ ...prev, level: prev.level + 1}) 
}

const eevee = Pokemon.init('Eevee');

halan

import { createStore } from 'redux'

const eevee = { especie: 'Eevee', level: 1 };

const eeveelution = (state = eevee, action) => {
  switch (action.type){
    case 'WATER_STONE':
      return { ...state, specie: 'Vaporeon' };
    case 'THUNDER_STONE':
      return { ...state, specie: 'Jolteon' };

halan

const map = transform => arr => {
  let transformed = []
  
  for(let i=0; i<=arr.length; i++) {
    transformed = [...transformed, transform(arr[i], i)]
  }
  
  return transformed
}