JavaScript Form Validation"

 Here is a full JavaScript program for form validation:

This program uses the <form> element to create a form with three fields: name, email, and password. Each field has a required attribute, which means that the user must fill out the field in order to submit the form. The email field also has a type attribute set to "email", which will check if the input is in the correct email format. The password field also has a minlength attribute set to 8, which will check if the input is at least 8 characters long.

The JavaScript code uses the onsubmit attribute to call the validateForm() function when the form is submitted. Inside the validateForm() function, it uses the getElementById method to select the form, name, email and password elements, and also the span elements that will display error messages. The function then initializes several variables, including isValid which is set to true.

The function then checks the value of each input field, and if it is empty, it sets the corresponding error message, and sets isValid to false. If the password field has a value but is less than 8 characters, it sets a different error message, and sets isValid to false.

If isValid is false, it calls the event.preventDefault() method to prevent the form from being submitted. The function then returns the value of isValid, which indicates whether the form is valid or not.

The CSS code defines the .error class, which is used to style the error messages. This can be used to change the color or font of the error messages.

This script can be implemented in any software that supports HTML and JavaScript, such as a text editor like Sublime or Atom, and a web browser like Chrome, Firefox or Safari.

And to further clarify, in order to run this program, you will need to save the code in an HTML file and open it in a web browser, this way the program can interact with the DOM (Document Object Model) and the browser can display the form and the error messages. You can also use a local development server like XAMPP, WAMP or LAMP which will allow you to run the program on a localhost environment, this will allow you to test the program without having to upload it to a live server and also the program can interact with the DOM. You can also use an online code editor like CodePen or JSFiddle to run the program, this option is useful if you want to share the program with others or you want to test it quickly.

Please let me know if you have any further questions.