A HTML form can allow people to enter data through a web page. This data can then be processed by their computer, or sent to the web-server and processed there. HTML forms can be used in many different ways. The most common use of a HTML form is to send a search query to a search engine, as with, for example, Google. This HTML form tutorial will give you all the information you need to start making your own HTML forms.
HTML form tutorial – basic elements
Each HTML form element corresponds to a pair of HTML tags. All of these are enclosed in the form tags <form></form>. The <form> tag attributes are used to configure the behavior of the form (how the form data will be processed).
The most common HTML form element is the <input> element. By setting the ‘type’ attribute, you can make the input element appear in a variety of different ways. A list follows:
type=”text”, a text field allowing a single line of text;
type=”checkbox”, a single checkbox;
type=”radio”, a single radio button;
type=”file”, a file selection control which can be used to upload a file;
type=”reset”, this creates a special button that when pressed will clear the values in the form;
type=”submit”, a submit button, the action of this button is determined in the ‘action’ attribute of the enclosing <form> tag.
type=”readonly”, a text field containing text that cannot be edited, often appears dimmed/grayed;
type=”hidden”, a text field that is not visible to the user, its data will be processed just the same as any other HTML form element;
type=”button”, a general purpose button, scripting code can be attached to it so that the desired action is performed;
type=”password”, a text field which will not show the characters typed into it, usually they will appear as asterisks so to hide the entered text from view.
Other form elements are created using a specific tag rather than the <input> tag, these are:
<button>, a general purpose button, similar to <input type=”button”> but it allows for greater variation including the use of images;
<selection list>, use this to create a drop-down list;
<textarea>, this form element creates a large box for entering multi-line text.
HTML Form Tutorial – labels
Labels are automatic for some HTML form elements, for instance buttons, but other HTML form elements like text fields and checkboxes do not have automatic labels. For these HTML form elements there is the <label> tag. Correct use of the label tag means that each label is associated with exactly one form element.
To apply a label to a form element, wrap the form element tag(s) with <label> tags. For example: <label><input type=”checkbox”>Label text</label>.
Another method for a applying a label to a form element is to use the ‘for’ attribute on the label tag. For example <label for=”my_checkbox”>Label text</label>. You then use a corresponding ‘id’ attribute on your form element: <input type=”checkbox” id=”my_checkbox”>.
HTML Form Tutorial – access keys
Access keys allow a user to give focus to a variety of HTML elements. This occurs when the user presses the designated key on their keyboard. The operation can differ depending on the user’s computer operating system; on a windows machine, the user will need to old the ‘alt’ key, on a Mac system the user will need to hold the ‘cmd’ key.
When using labels, the access key is generally attributed to the label of the form element. For instance, <label accesskey=”s”><input type=”text”>Search:</label>. In this example, when the user presses “alt-s” on a windows machine, the focus go to search field, meaning a cursor would appear in the search field. Access keys can be set on the following elements: <a>, <area>, <input>, <label>, <legend> and <textarea>.
HTML Form Tutorial Scripting
Forms may be combined with a variety of scripting languages in order to create dynamic web sites.
With server-side scripting, the data is processed on the webserver. A common scripting language used is PHP, but there are many others. Server-side scripting can ensure the security of the data processing, and ensure that the data is processed the same way for every user. The ‘method’ attribute on the <form> element determines how the data is sent to the sever. With method=”get” the data is appended to the URL, the script on the server must then anticipate this and process the data accordingly. With method=”post”, the data is sent directly to the webserver. Method=”post” allows for no limit on the amount of data being sent, and also for the data to be encrypted. Techniques for accessing method=”post” data will vary depending on the server-side scripting language being used.