如何避免表单验证不通过时跳转到PHP action指定URL？

The core problem with your current script is that it doesn’t stop the browser’s default form submission behavior when validation fails. When you click the submit button, both your validation function AND the form’s built-in submission process run at the same time. By the time location.reload() executes, the form has already started sending data to your PHP file, so the redirect still happens.

Here’s the corrected approach, with key improvements:

$(document).ready(function() {
  // Listen for the form's submit event (covers button clicks AND Enter key presses)
  $("#loginForm").submit(function(event) {
    if (!ValidateForm()) {
      event.preventDefault(); // Stop the form from submitting
      alert('One or more fields are empty. Please fill up all fields');
    }
  });
});

function ValidateForm() {
  var isFormValid = true;
  
  $('#loginForm input').each(function() {
    // Use trim() to catch inputs with only whitespace
    if ($(this).val().trim() === '') {
      isFormValid = false;
      return false; // Exit the loop early once an empty field is found
    }
  });
  
  return isFormValid;
}

Key Changes Explained: #

• Switched to form submit event: This ensures validation runs no matter how the user submits the form (clicking the button or pressing Enter in an input field).
• Added event.preventDefault(): This tells the browser to cancel its default submission action when validation fails, keeping the page from redirecting to your PHP file.
• Validation returns a boolean: Makes it easy to conditionally block submission based on whether the form is valid.
• Added trim(): Catches cases where a user enters only spaces (which would otherwise be considered a non-empty value).
• Early loop exit: Stops checking fields as soon as an empty one is found, making the validation more efficient.

You won’t need location.reload() anymore because preventing the default action keeps the page loaded with the user’s existing inputs intact.

Content of the question originates from Stack Exchange, question author Jimmy