JavaScript: Forms tutorial code snippet 6.

Intercepting a form's 'submit' button with the window 'alert()' method dialog box to provide form validation.

Simple form validation to test if user has entered any value into the form element.

Example of use of keyword 'this' to pass an object to a function.

Correct use of 'return false' and 'return true' within a function.

Use of 'focus()' to help user enter a value into the correct form element.