Understanding the conversation between the web browser and web server
that displays a form, processes the submitted form parameters, and
then displays a result.
Making the connection between the <form>
tag's action attribute and the
URL to which form parameters are submitted.
Using values from the $_SERVER auto-global array.
Accessing submitted form parameters in the $_GET
and $_POST auto-global arrays.
Accessing multivalued submitted form parameters.
Using show_form( ), validate_form(
), and process_form( ) functions to
modularize form handling.
Using a hidden form element to check whether a form has been
submitted.
Displaying error messages with a form.
Validating form elements: required elements, integers, floating-point
numbers, strings, date ranges, email addresses, and
<select> menus.
Defanging or removing submitted HTML and JavaScript before displaying
it.
Displaying default values for form elements.
Using helper functions to display form elements.
