CS 328 - Week 12 Lecture 1 - 2016-04-12

*   another popular use of JavaScript:
    to validate forms prior to submission

    *   PREVENT submission if they AREN'T up to
        standards!

    *   for a form element,
        you want to add an onsubmit attribute,

	you want to set the onsubmit attribute to
	a function that returns true or false;

	when a form is submitted, then,
	this function will be called;

	IF it returns true,
	the submission will be allowed to proceed;

	IF it returns false,
	the submission will NOT be allowed to proceed
	(the form will NOT be submitted)

*   see example: allFilled.js, three-value-form.php
                 (styled by three-value-form.js,
		  responded to by three-value-response.php)

		  ^ note that three-value-response STILL
		    needs to make sure values OK -- what if
		    someone is coming to it NOT from
		    three-value-form.php??