This tutorial will walk you through building a simple yet powerful Expense Tracker using the core web technologies: HTML, CSS, and JavaScript.

Project Overview

The Expense Tracker project is a web application that allows users to input and monitor their financial transactions, including income and expenses. The app summarises total income, expenses, and balance, enhancing users' ability to manage their finances effectively. Moreover, the application leverages local storage to persist data, ensuring the user's financial data remains intact after the browser refreshes.

Project Features:

A clean, user-friendly interface for transaction management.
Dynamic display of transactions, allowing users to see their financial activities in real time.
Calculation and display of balance, total income, and expenses.
Capability to add and remove transactions.
Data persistence using local storage.

Project Setting Up

Start by creating a project folder named expense-tracker. We'll create three primary files within this directory: index.html, style.css, and script.js.

1. index.html

The HTML code outlines the basic structure of the Expense Tracker, including elements for displaying the balance, income, expenses, transaction history, and a form for adding new transactions.

Let's create index.html and add the following code to it:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <link rel="stylesheet" href="style.css" />
    <title>Expense Tracker</title>
  </head>
  <body>
    <h2>Expense Tracker</h2>

    <div class="container">
      <h4>Your Balance</h4>
      <h1 id="balance">$0.00</h1>

      <div class="inc-exp-container">
        <div>
          <h4>Income</h4>
          <p id="money-plus" class="money plus">+$0.00</p>
        </div>
        <div>
          <h4>Expense</h4>
          <p id="money-minus" class="money minus">-$0.00</p>
        </div>
      </div>

      <h3>History</h3>
      <ul id="list" class="list">
        <!-- <li class="minus">
          Cash <span>-$400</span><button class="delete-btn">x</button>
        </li> -->
      </ul>

      <h3>Add new transaction</h3>
      <form id="form">
        <div class="form-control">
          <label for="text">Text</label>
          <input type="text" id="text" placeholder="Enter text..." />
        </div>
        <div class="form-control">
          <label for="amount"
            >Amount <br />
            (negative - expense, positive - income)</label
          >
          <input type="number" id="amount" placeholder="Enter amount..." />
        </div>
        <button class="btn">Add transaction</button>
      </form>
    </div>
    <script src="script.js"></script>
  </body>
</html>

2. style.css

The CSS file is responsible for styling the application, making it visually appealing and intuitive.

Let's create a CSS file named style.css and add the following CSS code to it:


@import url('https://fonts.googleapis.com/css?family=Lato&display=swap');

:root {
  --box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
}

* {
  box-sizing: border-box;
}

body {
  background-color: #f7f7f7;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  margin: 0;
  font-family: 'Lato', sans-serif;
}

.container {
  margin: 30px auto;
  width: 350px;
}

h1 {
  letter-spacing: 1px;
  margin: 0;
}

h3 {
  border-bottom: 1px solid #bbb;
  padding-bottom: 10px;
  margin: 40px 0 10px;
}

h4 {
  margin: 0;
  text-transform: uppercase;
}

.inc-exp-container {
  background-color: #fff;
  box-shadow: var(--box-shadow);
  padding: 20px;
  display: flex;
  justify-content: space-between;
  margin: 20px 0;
}

.inc-exp-container > div {
  flex: 1;
  text-align: center;
}

.inc-exp-container > div:first-of-type {
  border-right: 1px solid #dedede;
}

.money {
  font-size: 20px;
  letter-spacing: 1px;
  margin: 5px 0;
}

.money.plus {
  color: #2ecc71;
}

.money.minus {
  color: #c0392b;
}

label {
  display: inline-block;
  margin: 10px 0;
}

input[type='text'],
input[type='number'] {
  border: 1px solid #dedede;
  border-radius: 2px;
  display: block;
  font-size: 16px;
  padding: 10px;
  width: 100%;
}

.btn {
  cursor: pointer;
  background-color: #9c88ff;
  box-shadow: var(--box-shadow);
  color: #fff;
  border: 0;
  display: block;
  font-size: 16px;
  margin: 10px 0 30px;
  padding: 10px;
  width: 100%;
}

.btn:focus,
.delete-btn:focus {
  outline: 0;
}

.list {
  list-style-type: none;
  padding: 0;
  margin-bottom: 40px;
}

.list li {
  background-color: #fff;
  box-shadow: var(--box-shadow);
  color: #333;
  display: flex;
  justify-content: space-between;
  position: relative;
  padding: 10px;
  margin: 10px 0;
}

.list li.plus {
  border-right: 5px solid #2ecc71;
}

.list li.minus {
  border-right: 5px solid #c0392b;
}

.delete-btn {
  cursor: pointer;
  background-color: #e74c3c;
  border: 0;
  color: #fff;
  font-size: 20px;
  line-height: 20px;
  padding: 2px 5px;
  position: absolute;
  top: 50%;
  left: 0;
  transform: translate(-100%, -50%);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.list li:hover .delete-btn {
  opacity: 1;
}

3. script.js

JavaScript is the heart of our Expense Tracker, handling user interactions, DOM manipulations, and local storage operations.

Let's create a JavaScript file named script.js and add the following JavaScript code to it:

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() * 100000000);
}

// 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);

Open index.html in Browser

Let's open the index.html file in the browser, and you will be able to see the following screen:

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Expense Tracker Project with HTML, CSS, and JavaScript