Forms and Input

Html Course

• Form - Input Elements
• Other form elements

Usually a HTML Form is created to enable people who visit a webpage to enter information or select from a set of predefined options.

HTML Form

HTML forms are used to pass data to a server, to be processed by a programming language (like PHP, ASP, NodeJS). HTML forms can also be used with script languages, like JavaScript.
The <form> tag is used to create a HTML form.

<form action='#'>
 ... form elements
</form>

The <form> tag uses the following attributes:

• action='url' - Specifies the URL address where to send the form-data. This attribute is required, default is the curent URL if no address is added.
• accept-charset='charset_list' - Specifies the character-sets the server can handle for form-data (UTF-8, ISO-8859-1).
• autocomplete='on | off' - Allows the browser to fill in a field automatically (on) or requires the user to enter the information every time (off).
• enctype='content_type' - Specifies how form-data should be encoded before sending it to a server (application/x-www-form-urlencoded, multipart/form-data, or text/plain).
• method='get | post' - Specifies which HTTP method will be used to submit the form-data.
• name='text' - The name of the form.
• target='value' - Specifies where to open the action URL. Value can be: _blank, _self, _parent, _top or a framename

A form can contain input elements like text fields, checkboxes, submit buttons; and select lists, textarea, fieldset, and more.
All form elements are added inside <form> ... </form> tag.

Form - Input Elements

The input element is the most important form element. It is used to select user information, and can vary in many ways, depending on the type attribute.

Attributes of the <input /> tag:

• type='value' - Specifies the type of an input element (text, checkbox, radio, button, etc.)
• name='text' - Specifies a name for an input element
• accesskey='character' - Assigns an access key (keyboard shortcut) to an element for quicker access
• alt='text' - Specifies an alternative text for an image input (only for type='image')
• checked - When this attribute is added to a radio button or checkbox input, the input will be checked when the page loads
• disabled - Disables the control for user input
• maxlength='number' - Specifies the maximum number of characters the user can enter; for input elements with type: text, password, search, tel, url
• readonly - Indicates that the form input may not be modified by the user
• size='number' - Specifies the width of an input field (in number of characters)
• src='url' - When the input type is 'image', this attribute provides the location of the image to be used as a push button
• value='text' - Specifies the initial value for this input

Text field

Defines an one-line input field that a user can enter text into (the default width of a text field is 20 characters).

Password field

type='password' creates a text input element, but the characters are masked (shown as asterisks or circles).

Checkbox

Checkboxes let a user select one or more options of a limited number of choices.

Radio

Radio buttons let a user select only one of a limited number of choices, which have the same 'name' attribute.

File

Allows users to submit external files to the server. It is used for file uploads.
- This field is accompanied by a 'Browse' button, used to choose which document to be transferred to server.

Simple button

type='button' defines a clickable button, that does not do anything. The button type is most often used to activate a JavaScript function when a user clicks on the button.

Submit button

A submit button is used to send form data to a server. The data is sent to the page specified in the form's 'action' attribute.

Image for the Submit button

type='image' defines an image as a submit button. If a type='image' button is pressed, the form is submitted. The 'src' and 'alt' attribute are required.

Reset button

A reset button resets all form fields to their initial values.

Hidden

A hidden field is not visible for the user. Hidden controls can be used to pass some data to the server that the user cannot see or alter.

Other form elements

Textarea field

The <textarea> tag defines a multi-line text input control which can hold an unlimited number of characters.
The size of a textarea can be specified by the cols and rows attributes, or through CSS, with height and width properties.

Attributes for textarea:

• cols='number' - The width of textarea
• rows='number' - The number of rows, the hight of textarea
• name='text' - Specifies a name for a textarea
• disabled - Disables the control for user input
• readonly - Indicates that the form control may not be modified

Select list

The <select> </select> tag is used to create a select list (drop-down list).
This element should contain one ore more <option>...</option> tags. This tag defines an option within the select item.

<select name='a_name'>
 <option value='val1'>Option 1</option>
 <option value='val2'>Option 2</option>
 <option value='val3'>Option 3</option>
 ...
</select>

- If the 'value' attribute is not added in the <option> tag, its content will be the value that is sent to the server.

Attributes for <select>:

• size='number' - Specifies the number of visible options in a drop-down list. For values higher than 1, the options are displayed as a scrolling list with the specified number of options visible.
• name='text' - Specifies a name for a select list
• disabled - Disables the control for user input
• multiple - Allows the user to select more than one option from the list. When this attribute is absent, only single selections are allowed.

Attributes for <option>:

• selected - Makes this item selected when the form is initially displayed
• value='text' - Defines a value to assign to the option item.

<label> tag

The <label> tag defines a label for an input element.
Each label element is associated with one form control. The label element may contain the form control, or it may use the 'for' attribute to identify the control by its 'id' value.
- Syntax:
Or with the 'for' attribute:

<label for='input_id'>Text</label>
<input type='the_type' name='a_name' id='input_id' />

If the user clicks on the text within the label element, it toggles the control.
Example:

<form action='script.php' method='post'>
 <label>Text: <input type='text' name='text1' /></label><br>
 <label for='idc'>Check:</label> <input type='checkbox' name='a_name' id='idc' /><br>
 <input type='submit' value='Submit' />
</form>

This code will display:

<fieldset> and <legend> tags

The <fieldset> tag is used to logically group together elements in a form. It draws a box around the related form elements.
The <legend> tag defines a caption for the fieldset element.
Example:

<form action='script.php' method='post'>
 <fieldset> <legend style='margin-left:90%;'>Log in</legend>
 <label>Name: <input type='text' name='user' /></label><br />
 <label>Password: <input type='password' name='pass' size='16' /></label>
 </fieldset>
 <input type='submit' value='Submit' />
</form>

This code will display:

<optgroup> tag

The <optgroup> tag is used to group together related options in a select list. It uses two attributes:

• label='text' - Specifies the label for the option group
• disabled - Indicates that an option group should be disabled

Example:

<form action='script.php' method='post'>
 <p>What is your favorite fruit or vegetable?</p>
 <select name='fv' size='6'>
 <optgroup label='Fruits'>
 <option>Apple</option>
 <option>Banana</option>
 </optgroup>
 <optgroup label='Vegetables'>
 <option>Cabbage</option>
 <option>Tomato</option>
 </optgroup>
 </select>
</form>

Results of the code above in a browser:

<ul>
 <li>http://coursesweb.net/html/</li>
 <li>http://coursesweb.net/css/</li>
</ul>

.some_class {
  display: list-item;
}

var obj = {
 "courses": ["php", "javascript", "ajax"]
};
var jsonstr = JSON.stringify(obj);
alert(jsonstr);    // {"courses":["php","javascript","ajax"]}

$strhtml = '<body><div id="dv1">CoursesWeb.net</div></body>';
$dochtml = new DOMDocument();
$dochtml->loadHTML($strhtml);
$elm = $dochtml->getElementById("dv1");
echo $elm->nodeValue;    // CoursesWeb.net