Implementing Form Field Persistence on Webpage: HTML, CSS, and JavaScript Approach

To implement the feature of saving and populating form field values locally on the user's device, you can utilize the web storage API in JavaScript. Specifically, you can use the 'localStorage' object to store and retrieve the values. Here's a step-by-step guide on how to implement this feature using HTML, CSS, and JavaScript:

Step 1: Create the HTML Form

Start by creating an HTML form with various input fields such as text inputs, checkboxes, and dropdown menus. Each input field should have a unique 'id' attribute to identify it later in JavaScript.

<form>
  <label for="name">Name:</label>
  <input type="text" id="name" />

  <label for="email">Email:</label>
  <input type="email" id="email" />

  <label for="newsletter">Subscribe to Newsletter:</label>
  <input type="checkbox" id="newsletter" />

  <label for="country">Country:</label>
  <select id="country">
    <option value="usa">USA</option>
    <option value="canada">Canada</option>
    <option value="uk">UK</option>
  </select>

  <!-- Add more form fields as needed -->
  
  <button type="submit">Submit</button>
</form>

Step 2: Create the JavaScript Logic

Next, you'll need to write JavaScript logic to handle storing and retrieving form field values using the 'localStorage' object.

// Retrieve the form fields
const nameInput = document.getElementById('name');
const emailInput = document.getElementById('email');
const newsletterInput = document.getElementById('newsletter');
const countrySelect = document.getElementById('country');

// Check if form values are stored in localStorage
if (localStorage.getItem('formValues')) {
  // Parse the stored values from JSON
  const savedValues = JSON.parse(localStorage.getItem('formValues'));

  // Populate the form fields with the saved values
  nameInput.value = savedValues.name;
  emailInput.value = savedValues.email;
  newsletterInput.checked = savedValues.newsletter;
  countrySelect.value = savedValues.country;
}

// Event listener for form submission
document.querySelector('form').addEventListener('submit', function (e) {
  // Create an object to store form field values
  const formValues = {
    name: nameInput.value,
    email: emailInput.value,
    newsletter: newsletterInput.checked,
    country: countrySelect.value,
  };

  // Store the form field values in localStorage as JSON
  localStorage.setItem('formValues', JSON.stringify(formValues));
});

Step 3: Style the Form (Optional)

You can add CSS styles to the form to enhance its appearance. This step is optional and can be customized based on your preferences.

form {
  display: flex;
  flex-direction: column;
  max-width: 400px;
  margin: 0 auto;
}

label {
  margin-bottom: 5px;
}

input[type="checkbox"] {
  margin-left: 5px;
}

That's it! With these steps, the form field values will be stored locally on the user's device using 'localStorage'. When the user revisits the page, the values will be automatically populated in the respective fields.

If you want you can use 'sessionStorage' instead of 'localStorage'.

// Retrieve the form fields
const nameInput = document.getElementById('name');
const emailInput = document.getElementById('email');
const newsletterInput = document.getElementById('newsletter');
const countrySelect = document.getElementById('country');

// Check if form values are stored in sessionStorage
if (sessionStorage.getItem('formValues')) {
  // Parse the stored values from JSON
  const savedValues = JSON.parse(sessionStorage.getItem('formValues'));

  // Populate the form fields with the saved values
  nameInput.value = savedValues.name;
  emailInput.value = savedValues.email;
  newsletterInput.checked = savedValues.newsletter;
  countrySelect.value = savedValues.country;
}

// Event listener for form submission
document.querySelector('form').addEventListener('submit', function (e) {
  // Create an object to store form field values
  const formValues = {
    name: nameInput.value,
    email: emailInput.value,
    newsletter: newsletterInput.checked,
    country: countrySelect.value,
  };

  // Store the form field values in sessionStorage as JSON
  sessionStorage.setItem('formValues', JSON.stringify(formValues));
});