script.js

const balance = document.getElementById('balance');
const money_plus = document.getElementById('money-plus');
const money_minus = document.getElementById('money-minus');
const list = document.getElementById('list');
const form = document.getElementById('form');
const text = document.getElementById('text');
const amount = document.getElementById('amount');

// const dummyTransactions = [
//   {id: 1, text: 'Flower', amount: -20},
//   {id: 2, text: 'Salary', amount: 300},
//   {id: 3, text: 'Book', amount: -10},
//   {id: 4, text: 'Camera', amount: 150}
// ];

const localStorageTransactions = JSON.parse(localStorage.getItem('transactions'));
let transactions = localStorage.getItem('transactions') != null ? localStorageTransactions : [];

// add transaction
function addTransaction(e) {
  e.preventDefault();

  if(text.value.trim() === '' || amount.value.trim() === '') {
    alert('Please add a text and amount');
  } else {
    const transaction = {
      id: generateID(),
      text: text.value,
      amount: +amount.value
    }
    transactions.push(transaction);
    addTransactionDOM(transaction);
    updateValues();
    updateLocalStorage();
    text.value = '';
    amount.value = '';
  }
}

// generate random id
function generateID() {
  return Math.floor(Math.random() * 1000000000)
}

// add transactions to DOM list
function addTransactionDOM(transaction) {
  // get sign
  const sign = transaction.amount < 0 ? '-' : '+';

  const item = document.createElement('li');

  // add class based on value
  item.classList.add(transaction.amount < 0 ? 'minus' : 'plus');

  item.innerHTML = `
    ${transaction.text} <span>${sign}${Math.abs(transaction.amount)}</span> <button class="delete-btn" onclick="removeTransaction(${transaction.id})">x</button>
  `;
  list.appendChild(item);
}

// update the balance, income and expense
function updateValues() {
  const amounts = transactions.map(transaction => transaction.amount);
  const total = amounts.reduce((acc, item) => (acc += item), 0).toFixed(2);
  const income = amounts.filter(item => item > 0).reduce((acc,item) => (acc += item), 0).toFixed(2);
  const expense = (amounts.filter(item => item < 0).reduce((acc,item) => (acc += item), 0) * -1).toFixed(2);

  balance.innerText = `${total}€`;
  money_plus.innerText = `${income}€`;
  money_minus.innerText = `${expense}€`;
}

// remove transaction by id
function removeTransaction(id) {
  transactions = transactions.filter(transaction => transaction.id !== id);
  updateLocalStorage();
  init();
}

// update local storage transactions
function updateLocalStorage() {
  localStorage.setItem('transactions', JSON.stringify(transactions));
}

// init app
function init() {
  list.innerHTML = '';
  transactions.forEach(addTransactionDOM);
  updateValues();
}

init();

form.addEventListener('submit', addTransaction);