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.
<select id='numflowers'> <option value='0'>Number of Flowers
<option value='1'>1 <option value='2'>2 <option value='3'>3
<option value='4'>4 <option value='5'>5 <option value='6'>6
</select>
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:
<input type="radio" name="color1" value="red">Red
<input type="radio" name="color1" value="white">White
<input type="radio" name="color1" value="yellow">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 <div> 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 <div> differently. For example, the first group will start
with <div id="divColor1", the second will start with <div id="divColor2",
and so on. THIS IS IMPORTANT. When we pass variables onto the script, the only
thing that should change between the name of the <div> tags should be the
number. This is because we will use a loop to go through all the numbers. We
will pass through the name of the <div> tags to the javascript script,
and the script will add the numbers.
<div id='divColor1' style="display: none;"> Choose type of flower 1:
<input type="radio" name="color1" value="red">Red
<input type="radio" name="color1" value="white">White
<input type="radio" name="color1" value="yellow">Yellow
</div>
Now we have each option groups surrounded by a <div> tag. This will allow
us to change their visibility with javascript. I have put <div> tags
around the options, and added a submit button. Note: when adding <div>
tags inside a table, make sure they are contained within a <td> cell.
Something like <table><div><tr><td>< d><
r></div>< able> will not work for the same reason that adding
text outside of <td> cells inside a table doesn't work. If the stuff
inside the <div> 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 <div> tag. Here is the code:
<h3>Flower Order Form</h3> <form action="processorder.php"
method="post"> Select how many flowers you would like:
<select id='numflowers'> <option value='0'>Number of Flowers
<option value='1'>1 <option value='2'>2 <option value='3'>3
<option value='4'>4 <option value='5'>5
</select>
<div id='divColor1' style="display: none;"> Choose type of flower 1:
<input type="radio" name="color1" value="red">Red
<input type="radio" name="color1" value="white">White
<input type="radio" name="color1" value="yellow">Yellow
</div>
<div id='divColor2' style="display: none;"> Choose type of flower 2:
<input type="radio" name="color2" value="red">Red
<input type="radio" name="color2" value="white">White
<input type="radio" name="color2" value="yellow">Yellow
</div>
<div id='divColor3' style="display: none;"> Choose type of flower 3:
<input type="radio" name="color3" value="red">Red
<input type="radio" name="color3" value="white">White
<input type="radio" name="color3" value="yellow">Yellow
</div>
<div id='divColor4' style="display: none;"> Choose type of flower 4:
<input type="radio" name="color4" value="red">Red
<input type="radio" name="color4" value="white">White
<input type="radio" name="color4" value="yellow">Yellow
</div>
<div id='divColor5' style="display: none;"> Choose type of flower 5:
<input type="radio" name="color5" value="red">Red
<input type="radio" name="color5" value="white">White
<input type="radio" name="color5" value="yellow">Yellow
</div>
<div id='divColor6' style="display: none;"> Choose type of flower 6:
<input type="radio" name="color6" value="red">Red
<input type="radio" name="color6" value="white">White
<input type="radio" name="color6" value="yellow">Yellow
</div>
<input type="submit" value="Next Step"> </form>
We used css to hide the <div> tags. The next step is to use javascript to
show and hide each of the <div> 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 <div>
cells. There are 3 things we need to pass onto the script: the number of total
options, the name prefix for the <div> tags, and the number of options(to
end the loop). Here is the script that I wrote:
<script language="JavaScript"> function ShowMenu(num, menu, max) {
//starting at one, loop through until the number chosen by the user for(i = 1;
i <= num; i++){ //add number onto end of menu var menu2 = menu + i; //change
visibility to block, or 'visible' document.getElementById(menu2).style.display
= 'block'; } //make a number one more than the number inputed var num2 = num;
num2++; //hide menus if the viewer selects a number lower / his will hide every
number between the selected number // and the maximum //ex. if 3 is selected,
hide the <div> cells for 4, 5, //and 6 //loop until max is reached
while(num2 <= max){ var menu3 = menu + num2; //hide
document.getElementById(menu3).style.display = 'none'; //add one to loop
num2=num2+1; } } </script>
Add this code inside the <head> section of your page. Now we have one
less step; to call the function from the drop down box. Here is the code to do
that:
ShowMenu(document.getElementById('numflowers').value,'divCo <select
id='numflowers' onChange="javscript: lor', 6);"> <option
value='0'>Number of Flowers <option value='1'>1 <option
value='2'>2 <option value='3'>3 <option value='4'>4 <option
value='5'>5 <option value='6'>6
</select>
What this does is when the value is change, it will pass on the value, the name
prefix of the <div> cells, and the number of <div> cells. In the
first part, make sure the getElementById('numflowers') matches the 'id'
attribute in the <select> tag.
That's it! You can use this javascript function for anything, the only things
you have to change are the name prefixes and number of <div> cells, and
the id of the select tag. Using onChange, you can use a group of radio buttons
or a checkbox instead.
Here is the final code: <html> <head> <title>Flower Order
Form< itle> <script> function ShowMenu(num, menu, max) { //starting
at one, loop through until the number //chosen by the user for(i = 1; i <=
num; i++){ //add number onto end of menu var menu2 = menu + i; //change
visibility to block, or 'visible' document.getElementById(menu2).style.display
= 'block'; } //make a number one more than the number inputed var num2 = num;
num2++; //hide it if the viewer selects a number lower / his will hide every
number between the selected //number and the maximum //ex. if 3 is selected,
hide the <div> cells for //4, 5, and 6 //loop until max is reached
while(num2 <= max){ var menu3 = menu + num2; //hide
document.getElementById(menu3).style.display = 'none'; //add one to loop
num2=num2+1; } } </script> </head>
<body> <h3>Flower Order Form</h3> <form
action="processorder.php" method="post"> Select how many flowers you would
like:
<select id='numflowers' onChange="javscript:
ShowMenu(document.getElementById('numflowers').value, 'divColor', 6);">
<option value='0'>Number of Flowers <option value='1'>1 <option
value='2'>2 <option value='3'>3 <option value='4'>4 <option
value='5'>5
</select>
<div id='divColor1' style="display: none;"> Choose type of flower 1:
<input type="radio" name="color1" value="red">Red
<input type="radio" name="color1" value="white">White
<input type="radio" name="color1" value="yellow">Yellow
</div>
<div id='divColor2' style="display: none;"> Choose type of flower 2:
<input type="radio" name="color2" value="red">Red
<input type="radio" name="color2" value="white">White
<input type="radio" name="color2" value="yellow">Yellow
</div>
<div id='divColor3' style="display: none;"> Choose type of flower 3:
<input type="radio" name="color3" value="red">Red
<input type="radio" name="color3" value="white">White
<input type="radio" name="color3" value="yellow">Yellow
</div>
<div id='divColor4' style="display: none;"> Choose type of flower 4:
<input type="radio" name="color4" value="red">Red
<input type="radio" name="color4" value="white">White
<input type="radio" name="color4" value="yellow">Yellow
</div>
<div id='divColor5' style="display: none;"> Choose type of flower 5:
<input type="radio" name="color5" value="red">Red
<input type="radio" name="color5" value="white">White
<input type="radio" name="color5" value="yellow">Yellow
</div>
<div id='divColor6' style="display: none;"> Choose type of flower 6:
<input type="radio" name="color6" value="red">Red
<input type="radio" name="color6" value="white">White
<input type="radio" name="color6" value="yellow">Yellow
</div>
<input type="submit" value="Next Step"> </form>
</body> </html>
Thats all! Have a great day!
About the Author
Brian Zimmer is a graphics and web designer with over 4 years of experience in
Paint Shop Pro, HTML, CSS, Javascript, SEO, PHP, and MySQL. His services
include professional and affordable freelance web and graphic design. He is the
webmaster of http://www.zimmertech.com,
and you can contact him through email at brian@zimmertech.com.
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