✅ Real-Time Input Form Validation

👇 This is what it looks like 👇

👀 Live Demo

<form onsubmit="event.preventDefault()">
  Email Address:
  <input type="email" id="email" oninput="validateEmail()">
  <div class="error" id="emailError"></div>

  Password (at least 6 characters):
  <input type="password" id="password" oninput="validatePassword()">
  <div class="error" id="passwordError"></div>

  <button type="submit">Submit</button>
</form>

<style>
  .error {
    color: red;
    font-size: 0.9em;
    margin-bottom: 1em;
  }
</style>

<script>
function validateEmail() {
  const email = document.getElementById("email").value;
  const error = document.getElementById("emailError");
  error.textContent = email.includes("@") ? "" : "Invalid email format";
}

function validatePassword() {
  const pass = document.getElementById("password").value;
  const error = document.getElementById("passwordError");
  error.textContent = pass.length >= 6 ? "" : "Password must be at least 6 characters";
}
</script>

✅ Purpose & Benefits of This Template

Instant error checking while typing
User-friendly UX design
Simple validation logic using JS
Easy to customize even for beginners
Basic structure useful for real-world apps

🧩 Practical Use and Expansion of Form Validation

Real-time validation allows users to immediately check their input as they type, greatly reducing stress before submitting a form. By using the oninput event, you can create a mechanism that prevents mistakes without requiring a page reload.

For example, in validateEmail(), it checks for the presence of "@" with email.includes("@"). While this alone prevents basic format errors, combining it with regex can enable more precise validation.

🔍 Tips for Expanding Validation

For password checks, instead of just password.length >= 6, you can add conditions such as /[A-Z]/ or /\d/ using regular expressions to require a mix of letters and numbers.

Also, using innerText for error messages ensures that HTML tags are ignored, allowing you to safely and clearly communicate with users. Providing individual error messages for each field is a key technique for improving UX.

This template covers the basics of validation well, so feel free to expand it by adding new fields or adjusting styles based on your specific needs.