HTML and CSS Reference
In-Depth Information
high
: defines the lower numeric bound of the high end of the measured range; a value between
the
high
and
max
attributes is considered a high measurement. This attribute's value must be
less than the maximum value (
max
attribute), and it also must be greater than the low value and
minimum value (
low
attribute and
min
attribute, respectively), if they are specified. If unspecified,
or if greater than the maximum value, the high value is equal to the maximum value.
optimum
: indicates the optimal numeric value. It must be within the range as defined by the
min
and
max
attributes. When used with the
low
and
high
attributes, it gives an indication where
along the range is considered preferable. For example, if the optimum value falls between the
min
attribute and the
low
attribute, then lower values are considered preferable.
form
: associates the element with a
form
element that has ownership of the
meter
element. For
example, a
meter
might display a range corresponding to an
input type="number"
. The
form
attribute is only necessary if the
meter
element is being used as a form-associated element; even
then, it may be omitted if the element appears as a descendant of a
form
element.
progress
Somewhat similar to the
meter
element (and also new in HTML5), the
progress
element represents the
current stage in the completion of a task, rendered as a graphical bar with a filled portion to indicate the
progress completed. This element is most useful in combination with JavaScript to dynamically update its
value as progress is made in an application, animating the bar filling up to completion.
The progress can be indeterminate with no specified value, indicating that progress is being made but that
it's not yet clear how much work is left before the task is done. For example, you might display an
indeterminate progress bar while waiting for a response from a server before a process can begin:
<p>Upload: <progress>starting...</progress></p>
Or the progress can be a number in the range of zero to a maximum, giving the portion of work that has
been completed thus far, specified by the optional
value
and
max
attributes:
<p>Processing: <progress max="100" value="77">77%</progress</p>
The
progress
element doesn't have a
min
attribute; the minimum is always 0. The maximum can be any
positive number you like, and the
value
attribute must fall within the specified range. For rendering
purposes, any value less than 0 is treated as 0, and any value greater than the maximum is treated as
equal to the maximum. The default maximum is 1, hence the value must be a decimal in the range of 0 to
1 if the
max
attribute is absent.
This is a phrasing element that requires both a start and end tag, and may contain only text and other
phrasing elements. As with the
meter
element, browsers that support the
progress
element will render a
graphical bar, shown in Figure 8-31. Older and non-supporting browsers will display the element's
contents, so that content should communicate the same value to offer a readable fallback:
<p>Check out: <progress max="5" value="3">Step 3 of 5</progress></p>