Computer Science M8

HTML Input Attributes

The value Attribute

The value attribute specifies the initial value for an input field:

Example

<form action="">
First name:<br>
<input type="text" name="firstname" value="John">
</form>

The readonly Attribute

The readonly attribute specifies that the input field is read only (cannot be changed):

Example

<form action="">
First name:<br>
<input type="text" name="firstname" value="John" readonly>
</form>

The disabled Attribute

The disabled attribute specifies that the input field is disabled.

A disabled input field is unusable and un-clickable, and its value will not be sent when submitting the form:

Example

<form action="">
First name:<br>
<input type="text" name="firstname" value="John" disabled>
</form>

The size Attribute

The size attribute specifies the size (in characters) for the input field:

Example

<form action="">
First name:<br>
<input type="text" name="firstname" value="John" size="40">
</form>

The maxlength Attribute

The maxlength attribute specifies the maximum allowed length for the input field:

Example

<form action="">
First name:<br>
<input type="text" name="firstname" maxlength="10">
</form>

With a maxlength attribute, the input field will not accept more than the allowed number of characters.

The maxlength attribute does not provide any feedback. If you want to alert the user, you must write JavaScript code.

Note: Input restrictions are not foolproof, and JavaScript provides many ways to add illegal input. To safely restrict input, it must be checked by the receiver (the server) as well!


HTML5 Attributes

HTML5 added the following attributes for <input>:

  • autocomplete
  • autofocus
  • form
  • formaction
  • formenctype
  • formmethod
  • formnovalidate
  • formtarget
  • height and width
  • list
  • min and max
  • multiple
  • pattern (regexp)
  • placeholder
  • required
  • step

and the following attributes for <form>:

  • autocomplete
  • novalidate

The autocomplete Attribute

The autocomplete attribute specifies whether a form or input field should have autocomplete on or off.

When autocomplete is on, the browser automatically complete the input values based on values that the user has entered before.

Tip: It is possible to have autocomplete "on" for the form, and "off" for specific input fields, or vice versa.

The autocomplete attribute works with <form> and the following <input> types: text, search, url, tel, email, password, datepickers, range, and color.

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Example

An HTML form with autocomplete on (and off for one input field):

<form action="/action_page.php" autocomplete="on">
  First name:<input type="text" name="fname"><br>
  Last name: <input type="text" name="lname"><br>
  E-mail: <input type="email" name="email" autocomplete="off"><br>
  <input type="submit">
</form>

Tip: In some browsers you may need to activate the autocomplete function for this to work.


The novalidate Attribute

The novalidate attribute is a <form> attribute.

When present, novalidate specifies that the form data should not be validated when submitted.

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Example

Indicates that the form is not to be validated on submit:

<form action="/action_page.php" novalidate>
  E-mail: <input type="email" name="user_email">
  <input type="submit">
</form>

The autofocus Attribute

The autofocus attribute specifies that the input field should automatically get focus when the page loads.

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Example

Let the "First name" input field automatically get focus when the page loads:

First name:<input type="text" name="fname" autofocus>

The form Attribute

The form attribute specifies one or more forms an <input> element belongs to.

Tip: To refer to more than one form, use a space-separated list of form ids.

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Example

An input field located outside the HTML form (but still a part of the form):

<form action="/action_page.php" id="form1">
  First name: <input type="text" name="fname"><br>
  <input type="submit" value="Submit">
</form>

Last name: <input type="text" name="lname" form="form1">

The formaction Attribute

The formaction attribute specifies the URL of a file that will process the input control when the form is submitted.

The formaction attribute overrides the action attribute of the <form> element.

The formaction attribute is used with type="submit" and type="image".

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Example

An HTML form with two submit buttons, with different actions:

<form action="/action_page.php">
  First name: <input type="text" name="fname"><br>
  Last name: <input type="text" name="lname"><br>
  <input type="submit" value="Submit"><br>
  <input type="submit" formaction="/action_page2.php"
  value="Submit as admin"
>

</form>

The formenctype Attribute

The formenctype attribute specifies how the form data should be encoded when submitted (only for forms with method="post").

The formenctype attribute overrides the enctype attribute of the <form> element.

The formenctype attribute is used with type="submit" and type="image".

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Example

Send form-data that is default encoded (the first submit button), and encoded as "multipart/form-data" (the second submit button):

<form action="/action_page_binary.asp" method="post">
  First name: <input type="text" name="fname"><br>
  <input type="submit" value="Submit">
  <input type="submit" formenctype="multipart/form-data"
  value="Submit as Multipart/form-data"
>

</form>

The formmethod Attribute

The formmethod attribute defines the HTTP method for sending form-data to the action URL.

The formmethod attribute overrides the method attribute of the <form> element.

The formmethod attribute can be used with type="submit" and type="image".

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Example

The second submit button overrides the HTTP method of the form:

<form action="/action_page.php" method="get">
  First name: <input type="text" name="fname"><br>
  Last name: <input type="text" name="lname"><br>
  <input type="submit" value="Submit">
  <input type="submit" formmethod="post" formaction="action_page_post.asp"
  value="Submit using POST"
>

</form>

The formnovalidate Attribute

The formnovalidate attribute overrides the novalidate attribute of the <form> element.

The formnovalidate attribute can be used with type="submit".

OperaSafariChromeFirefoxInternet Explorer

Example

A form with two submit buttons (with and without validation):

<form action="/action_page.php">
  E-mail: <input type="email" name="userid"><br>
  <input type="submit" value="Submit"><br>
  <input type="submit" formnovalidate value="Submit without validation">
</form>

The formtarget Attribute

The formtarget attribute specifies a name or a keyword that indicates where to display the response that is received after submitting the form.

The formtarget attribute overrides the target attribute of the <form> element.

The formtarget attribute can be used with type="submit" and type="image".

 

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