HTML5

The following extract shows how a messaging client's text entry could be arbitrarily restricted to a fixed number of characters, thus forcing any conversation through this medium to be terse and discouraging intelligent discourse.

<label>What are you doing? <input name=status maxlength=140></label>

In the following example, the existing product identifiers cannot be modified, but they are still displayed as part of the form, for consistency with the row representing a new product (where the identifier is not yet filled in).

<form action="products.cgi" method=post enctype="multipart/form-data">
 <table>
  <tr> <th> Product ID <th> Product name <th> Price <th> Action
  <tr>
   <td> <input readonly name="1.pid" value="H412">
   <td> <input required name="1.pname" value="Floor lamp Ulke">
   <td> $<input required type=number min=0 step=0.01 name="1.pprice" value="49.99">
   <td> <button formnovalidate name="action" value="delete:1">Delete</button>
  <tr>
   <td> <input readonly name="2.pid" value="FG28">
   <td> <input required name="2.pname" value="Table lamp Ulke">
   <td> $<input required type=number min=0 step=0.01 name="2.pprice" value="24.99">
   <td> <button formnovalidate name="action" value="delete:2">Delete</button>
  <tr>
   <td> <input required name="3.pid" value="" pattern="[A-Z0-9]+">
   <td> <input required name="3.pname" value="">
   <td> $<input required type=number min=0 step=0.01 name="3.pprice" value="">
   <td> <button formnovalidate name="action" value="delete:3">Delete</button>
 </table>
 <p> <button formnovalidate name="action" value="add">Add</button> </p>
 <p> <button name="action" value="update">Save</button> </p>
</form>

The following form has two required fields, one for an e-mail address and one for a password. It also has a third field that is only considered valid if the user types the same password in the password field and this third field.

<h1>Create new account</h1>
<form action="/newaccount" method=post
      oninput="up2.setCustomValidity(up2.value != up.value ? 'Passwords do not match.' : '')">
 <p>
  <label for="username">E-mail address:</label>
  <input id="username" type=email required name=un>
 <p>
  <label for="password1">Password:</label>
  <input id="password1" type=password required name=up>
 <p>
  <label for="password2">Confirm password:</label>
  <input id="password2" type=password name=up2>
 <p>
  <input type=submit value="Create account">
</form>

The following extract shows how an e-mail client's "Cc" field could accept multiple e-mail addresses.

<label>Cc: <input type=email multiple name=cc></label>

If the user had, amongst many friends in his user contacts database, two friends "Arthur Dent" (with address "art@example.net") and "Adam Josh" (with address "adamjosh@example.net"), then, after the user has typed "a", the user agent might suggest these two e-mail addresses to the user.

The page could also link in the user's contacts database from the site:

<label>Cc: <input type=email multiple name=cc list=contacts></label>
...
<datalist id="contacts">
 <option value="hedral@damowmow.com">
 <option value="pillar@example.com">
 <option value="astrophy@cute.example">
 <option value="astronomy@science.example.org">
</datalist>

Suppose the user had entered "bob@example.net" into this text field, and then started typing a second e-mail address starting with "a". The user agent might show both the two friends mentioned earlier, as well as the "astrophy" and "astronomy" values given in the datalist element.

The following extract shows how an e-mail client's "Attachments" field could accept multiple files for upload.

<label>Attachments: <input type=file multiple name=att></label>

For example, the following snippet:

<label> Part number:
 <input pattern="[0-9][A-Z]{3}" name="part"
        title="A part number is a digit followed by three uppercase letters."/>
</label>

...could cause the UA to display an alert such as:

A part number is a digit followed by three uppercase letters.
You cannot submit this form when the field is incorrect.

The following date control limits input to dates that are before the 1980s:

<input name=bday type=date max="1979-12-31">

The following number control limits input to whole numbers greater than zero:

<input name=quantity required type=number min=1 value=1>

The following range control only accepts values in the range 0..1, and allows 256 steps in that range:

<input name=opacity type=range min=0 max=1 step=0.00392156863>

The following control allows any time in the day to be selected, with any accuracy (e.g. thousandth-of-a-second accuracy or more):

<input name=favtime type=time step=any>

Normally, time controls are limited to an accuracy of one minute.

This URL field offers some suggestions.

<label>Homepage: <input name=hp type=url list=hpurls></label>
<datalist id=hpurls>
 <option value="http://www.google.com/" label="Google">
 <option value="http://www.reddit.com/" label="Reddit">
</datalist>

Other URLs from the user's history might show also; this is up to the user agent.

This example demonstrates how to design a form that uses the autocompletion list feature while still degrading usefully in legacy user agents.

If the autocompletion list is merely an aid, and is not important to the content, then simply using a datalist element with children option elements is enough. To prevent the values from being rendered in legacy user agents, they need to be placed inside the value attribute instead of inline.

<p>
 <label>
  Enter a breed:
  <input type="text" name="breed" list="breeds">
  <datalist id="breeds">
   <option value="Abyssinian">
   <option value="Alpaca">
   <!-- ... -->
  </datalist>
 </label>
</p>

However, if the values need to be shown in legacy UAs, then fallback content can be placed inside the datalist element, as follows:

<p>
 <label>
  Enter a breed:
  <input type="text" name="breed" list="breeds">
 </label>
 <datalist id="breeds">
  <label>
   or select one from the list:
   <select name="breed">
    <option value=""> (none selected)
    <option>Abyssinian
    <option>Alpaca
    <!-- ... -->
   </select>
  </label>
 </datalist>
</p>

The fallback content will only be shown in UAs that don't support datalist. The options, on the other hand, will be detected by all UAs, even though they are not children of the datalist element.

Note that if an option element used in a datalist is selected, it will be selected by default by legacy UAs (because it affects the select), but it will not have any effect on the input element in UAs that support datalist.

Here is an example of a mail configuration user interface that uses the placeholder attribute:

<fieldset>
 <legend>Mail Account</legend>
 <p><label>Name: <input type="text" name="fullname" placeholder="John Ratzenberger"></label></p>
 <p><label>Address: <input type="email" name="address" placeholder="john@example.net"></label></p>
 <p><label>Password: <input type="password" name="password"></label></p>
 <p><label>Description: <input type="text" name="desc" placeholder="My Email Account"></label></p>
</fieldset>