HTML JavaScript Advanced (Local Storage + Data Save) #7

Part 6 मा हामीले DOM प्रयोग गरेर dynamic website बनायौँ।अब Part 7 मा — data save गर्ने (Local Storage) सिकौँ 🚀

👉 अब हाम्रो website “real app” जस्तो behave गर्ने छ 😍

🔍 Local Storage भनेको के हो?

👉 Local Storage = Browser भित्र data save गर्ने system

👉 मतलब:

  • Page reload भए पनि data हराउँदैन ❌
  • Browser बन्द गरे पनि data रहन्छ ✅

👉 Example:To-Do list बनायौ → reload गर्दा पनि tasks रहन्छ

⚡ Local Storage किन important छ?

👉 बिना Local Storage:❌ Data हराउँछ❌ User experience खराब हुन्छ

👉 Local Storage प्रयोग गर्दा:✅ Data persistent हुन्छ✅ Real app feeling आउँछ✅ Offline पनि काम गर्छ

🧠 Basic Methods (Must Know)

1. Data Save गर्ने

localStorage.setItem("name", "Rohan");

2. Data Get गर्ने

var data = localStorage.getItem("name");
console.log(data);

3. Data Delete गर्ने

localStorage.removeItem("name");

4. All Clear गर्ने

localStorage.clear();

🎯 Important Concept (JSON)

👉 Local Storage string मात्र store गर्छ

👉 Object / Array save गर्न:

var arr = ["Task 1", "Task 2"];

localStorage.setItem("tasks", JSON.stringify(arr));

👉 Retrieve गर्दा:

var data = JSON.parse(localStorage.getItem("tasks"));

🔥 Mini Project — Persistent To-Do App (Upgrade Version)

👉 अब हामी Part 6 को To-Do App लाई upgrade गर्छौँ 😍👉 Reload भए पनि tasks हराउने छैन

💻 Full Code (Copy Paste Ready)

<!DOCTYPE html>
<html>
<head>
  <title>To-Do App (Saved)</title>
  <style>
    body {
      font-family: Arial;
      text-align: center;
      margin-top: 50px;
    }
    input {
      padding: 10px;
      width: 200px;
    }
    button {
      padding: 10px;
      margin-left: 5px;
      cursor: pointer;
    }
    li {
      margin: 10px;
      list-style: none;
    }
  </style>
</head>

<body>

<h2>My To-Do List (Saved) 📝</h2>

<input type="text" id="task" placeholder="Enter task">
<button onclick="addTask()">Add</button>

<ul id="list"></ul>

<script>

let tasks = JSON.parse(localStorage.getItem("tasks")) || [];

// Page load हुँदा data show गर्ने
function showTasks() {
  let list = document.getElementById("list");
  list.innerHTML = "";

  tasks.forEach((task, index) => {
    let li = document.createElement("li");

    li.innerHTML = task + 
    " <button onclick='deleteTask(" + index + ")'>❌</button>";

    list.appendChild(li);
  });
}

// Add Task
function addTask() {
  let input = document.getElementById("task");
  let value = input.value;

  if (value === "") {
    alert("Task खाली छ ❌");
    return;
  }

  tasks.push(value);
  localStorage.setItem("tasks", JSON.stringify(tasks));

  input.value = "";
  showTasks();
}

// Delete Task
function deleteTask(index) {
  tasks.splice(index, 1);
  localStorage.setItem("tasks", JSON.stringify(tasks));
  showTasks();
}

// Initial Load
showTasks();

</script>

</body>
</html>

🎯 के सिक्यौँ?

✅ Local Storage के हो✅ setItem / getItem / removeItem✅ JSON stringify / parse✅ Data save गरेर reload पछि पनि राख्ने✅ Persistent To-Do App बनाउने

🧠 Real-Life Understanding

👉 HTML = घर 🏠👉 CSS = सजावट 🎨👉 JavaScript = control ⚡👉 Local Storage = storage (घरको locker) 🔐

👉 अब:

  • User data हराउँदैन
  • Website “app” जस्तो हुन्छ

⚠️ Important Notes (Interview Level 🔥)

👉 Local Storage Limit: ~5MB👉 Only string support👉 Same browser मा मात्र काम गर्छ👉 Sensitive data store नगर्नुहोस् ❌

🚀 Next Level Challenge (Try Yourself)

👉 Add these features:

  • ✅ Edit task
  • ✅ Mark as completed ✔️
  • ✅ Clear all button
  • ✅ Task count

🚀 Part 8 मा के आउँछ?

👉 Dark Mode Toggle 🌙👉 Theme switching👉 UI interaction advanced

👉 Practice गर 👨‍💻👉 यो To-Do App लाई upgrade गर

🔥 अब तिमी beginner होइन — builder भइसकेको छौ 🚀

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