<html lang="en"><head><meta charset="utf-8"><title>Prevent Default Demo</title></head><body><form action="/examples/html/action.php" method="post" id="users"> <label>First Name:</label> <input type="text" name="first-name" id="firstName"> <input type="submit" value="Submit" id="submitBtn"></form><script> var btn = document.getElementById("submitBtn"); btn.addEventListener("click", function(event) { var name = document.getElementById("firstName").value; alert("Sorry, " + name + ". The preventDefault() won't let you submit this form!"); event.preventDefault(); // Prevent form submission });</script>