HTML Forms
An HTML form is used to collect user input. The user input is most often sent to a server for processing.
The <form> Element
The HTML <form>
element is used to create an HTML form for user input:
The <form>
element is a container for different types of input elements, such as: text fields, checkboxes, radio buttons, submit buttons, etc.
The <input> Element
The HTML <input>
element is the most used form element.
An <input>
element can be displayed in many ways, depending on the type
attribute.
Here are some examples:
Type | Description |
---|---|
<input type="text"> | Displays a single-line text input field |
<input type="radio"> | Displays a radio button (for selecting one of many choices) |
<input type="checkbox"> | Displays a checkbox (for selecting zero or more of many choices) |
<input type="submit"> | Displays a submit button (for submitting the form) |
<input type="button"> | Displays a clickable button |
Text Fields
The <input type="text">
defines a single-line input field for text input.
The <label> Element
Notice the use of the <label>
element in the example above.
The <label>
tag defines a label for many form elements.
The <label>
element is useful for screen-reader users, because the screen-reader will read out loud the label when the user focus on the input element.
The <label>
element also help users who have difficulty clicking on very small regions (such as radio buttons or checkboxes) - because when the user clicks the text within the <label>
element, it toggles the radio button/checkbox.
The for
attribute of the <label>
tag should be equal to the id
attribute of the <input>
element to bind them together.
Radio Buttons
The <input type="radio">
defines a radio button.
Radio buttons let a user select ONE of a limited number of choices.
Checkboxes
The <input type="checkbox">
defines a checkbox.
Checkboxes let a user select ZERO or MORE options of a limited number of choices.
The Submit Button
The <input type="submit">
defines a button for submitting the form data to a form-handler.
The form-handler is typically a file on the server with a script for processing input data.
The form-handler is specified in the form's action
attribute.
The Name Attribute for <input>
Notice that each input field must have a name
attribute to be submitted.
If the name
attribute is omitted, the value of the input field will not be sent at all.
The Action Attribute
The action
attribute defines the action to be performed when the form is submitted.
Usually, the form data is sent to a file on the server when the user clicks on the submit button.
In the example below, the form data is sent to a file called "action_page.php". This file contains a server-side script that handles the form data:
The Target Attribute
The target
attribute specifies where to display the response that is received after submitting the form.
The target
attribute can have one of the following values:
Value | Description |
---|---|
_blank | The response is displayed in a new window or tab |
_self | The response is displayed in the current window |
_parent | The response is displayed in the parent frame |
_top | The response is displayed in the full body of the window |
framename | The response is displayed in a named iframe |
The default value is _self
which means that the response will open in the current window.
The Method Attribute
The method
attribute specifies the HTTP method to be used when submitting the form data.
The form-data can be sent as URL variables (with method="get"
) or as HTTP post transaction (with method="post"
).
The default HTTP method when submitting form data is GET.
The HTML <form> Elements
The HTML <form>
element can contain one or more of the following form elements:
<input>
<label>
<select>
<textarea>
<button>
<fieldset>
<legend>
<datalist>
<output>
<option>
<optgroup>
The <input> Element
One of the most used form element is the <input>
element.
The <input>
element can be displayed in several ways, depending on the type
attribute.
The <label> Element
The <label>
element defines a label for several form elements.
The <label>
element is useful for screen-reader users, because the screen-reader will read out loud the label when the user focus on the input element.
The <label>
element also help users who have difficulty clicking on very small regions (such as radio buttons or checkboxes) - because when the user clicks the text within the <label>
element, it toggles the radio button/checkbox.
The for
attribute of the <label>
tag should be equal to the id
attribute of the <input>
element to bind them together.
The <select> Element
The <select>
element defines a drop-down list:
The <option>
elements defines an option that can be selected.
By default, the first item in the drop-down list is selected.
To define a pre-selected option, add the selected
attribute to the option:
Visible Values:
Use the size
attribute to specify the number of visible values:
Allow Multiple Selections:
Use the multiple
attribute to allow the user to select more than one value:
The <textarea> Element
The <textarea>
element defines a multi-line input field (a text area):
The <button> Element
The <button>
element defines a clickable button:
The <fieldset> and <legend> Elements
The <fieldset>
element is used to group related data in a form.
The <legend>
element defines a caption for the <fieldset>
element.
The <datalist> Element
The <datalist>
element specifies a list of pre-defined options for an <input>
element.
Users will see a drop-down list of the pre-defined options as they input data.
The list
attribute of the <input>
element, must refer to the id
attribute of the <datalist>
element.
The <output> Element
The <output>
element represents the result of a calculation (like one performed by a script).
HTML Input Types
Here are the different input types you can use in HTML:
<input type="button">
<input type="checkbox">
<input type="color">
<input type="date">
<input type="datetime-local">
<input type="email">
<input type="file">
<input type="hidden">
<input type="image">
<input type="month">
<input type="number">
<input type="password">
<input type="radio">
<input type="range">
<input type="reset">
<input type="search">
<input type="submit">
<input type="tel">
<input type="text">
<input type="time">
<input type="url">
<input type="week">
Input Type Text
Input Type Password
Input Type Submit
The form-handler is typically a server page with a script for processing input data.
The form-handler is specified in the form's action
attribute:
Input Type Reset
Input Type Radio
Radio buttons let a user select ONLY ONE of a limited number of choices.
Input Type Checkbox
Checkboxes let a user select ZERO or MORE options of a limited number of choices.
Input Type Button
Input Type Color
Depending on browser support, a color picker can show up in the input field.
Input Type Date
Depending on browser support, a date picker can show up in the input field.
You can also use the min
and max
attributes to add restrictions to dates:
Input Type Datetime-local
Depending on browser support, a date picker can show up in the input field.
Input Type Email
Depending on browser support, the e-mail address can be automatically validated when submitted.
Some smartphones recognize the email type, and add ".com" to the keyboard to match email input.
Input Type Image
The path to the image is specified in the src
attribute.
Input Type File
Input Type Hidden
A hidden field lets web developers include data that cannot be seen or modified by users when a form is submitted.
A hidden field often stores what database record that needs to be updated when the form is submitted.
Note: While the value is not displayed to the user in the page's content, it is visible (and can be edited) using any browser's developer tools or "View Source" functionality. Do not use hidden inputs as a form of security!
Input Type Month
Depending on browser support, a date picker can show up in the input field.
Input Type Number
You can also set restrictions on what numbers are accepted.
The following example displays a numeric input field, where you can enter a value from 1 to 5:
Input Restrictions
Here is a list of some common input restrictions:
Attribute | Description |
---|---|
checked | Specifies that an input field should be pre-selected when the page loads (for type="checkbox" or type="radio") |
disabled | Specifies that an input field should be disabled |
max | Specifies the maximum value for an input field |
maxlength | Specifies the maximum number of character for an input field |
min | Specifies the minimum value for an input field |
pattern | Specifies a regular expression to check the input value against |
readonly | Specifies that an input field is read only (cannot be changed) |
required | Specifies that an input field is required (must be filled out) |
size | Specifies the width (in characters) of an input field |
step | Specifies the legal number intervals for an input field |
value | Specifies the default value for an input field |
You will learn more about input restrictions in the next chapter.
The following example displays a numeric input field, where you can enter a value from 0 to 100, in steps of 10. The default value is 30
Input Type Range
The <input type="range">
defines a control for entering a number whose exact value is not important (like a slider control). Default range is 0 to 100. However, you can set restrictions on what numbers are accepted with the min
, max
, and step
attributes:
Input Type Search
Input Type Tel
Input Type Time
Depending on browser support, a time picker can show up in the input field.
Input Type Url
Depending on browser support, the url field can be automatically validated when submitted.
Some smartphones recognize the url type, and adds ".com" to the keyboard to match url input.
Input Type Week
Depending on browser support, a date picker can show up in the input field.
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