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Interactive Forms

by Brian Zimmer

Why interactive forms?

Forms are easy enough to create when they are simple, like
search boxes. But what if you need them to be complex? How
about changing the forms based on input by the viewer? This
is where interactive forms using Javascript and HTML can
help. I'll use a simple example on how interactive forms can
be useful.

The problem

I am going to use a business project as an example to teach
interactive forms. Imagine that we are creating a ordering
system for flowers. We would like the customer to be able to
order a bouquet of flowers. The customer can choose to have
any number of flowers in the bouqet from 1 to 6. For each
flower, the customer can choose a type of flower, and there
are 3 different kinds of flowers. Now imagine all these
options as a regular form. There would be 18 options to
choose from, even if you only wanted one flower! This would
be ugly! In this tutorial we will learn how we can show and
hide form elements depending on the input by the customer.
Now let's get started!

Creating the interactive form
-HTML

We are going to create a page where you can enter the
information for ordering flowers. We've decided on having a
drop down menu to select the number of flowers, and then for
the number selected, display that number of options to
choose the type of flower. We'll start by creating the HTML
forms. First we will write the html code for the form.


Number of Flowers
1
2
3
4
5
6

This will create a menu.

Next we need to create the form where the customer will
choose the type of flower they would like. We will let them
choose between a red rose, a white rose, and a yellow rose.
I am going to use radio buttons for the selection. Here is
the code:

Red

White

Yellow


For this tutorial, I assume you have a basic knowledge of
HTML. All of these pages still need mandatory tags, but I
left them out because of the size they would take up. Notice
how I made all the options the same name. This is so they
are grouped together, and only one option can be choosen.

This is what it will look like: 0 Red 0 White 0 Yellow

Duplicate this code 6 times, for each of the flower. But
every time you see "color1", change that to a different name
so they are all seperate. I will use "color1", "color2",
"color3", and so on.

Now we need to put all of this together into an ordering
form. But we need to add something so that the forms can
disappear. We will add tags around each of the flower
type selection rows. Enter the following code around each of
the groups of options. Make sure that for each one, you
label the id tag for the differently. For example, the
first group will start with < able>
will not work for the same reason that adding text outside
of cells inside a table doesn't work. If the stuff
inside the tag is showing up, tables may be your
problem. To fix this, either don't use tables, or create an
entire seperate table for the information inside the
tag. Here is the code:

Flower Order Form

Select how many flowers you would like:


Number of Flowers
1
2
3
4
5




Choose type of flower 1:


Red

White

Yellow




Choose type of flower 2:


Red

White

Yellow




Choose type of flower 3:


Red

White

Yellow




Choose type of flower 4:


Red

White

Yellow




Choose type of flower 5:


Red

White

Yellow




Choose type of flower 6:


Red

White

Yellow








We used css to hide the tags. The next step is to use
javascript to show and hide each of the cells
depending on what is selected in the drop down menu. We will
start out by making a javascript function, then I will
explain the code and link it up with the drop down menu.
Javascript

We are going to create a function that will show and hide
the cells. There are 3 things we need to pass onto the
script: the number of total options, the name prefix for the
tags, and the number of options(to end the loop). Here
is the script that I wrote:


function ShowMenu(num, menu, max)
{
//starting at one, loop through until the number chosen
by the user
for(i = 1; i