Applicability
The Technique is applicable to any technology that supports the display of additional content on pointer hover.
This technique relates to Success Criterion 1.4.13: Content on Hover or Focus (Sufficient).
Description
Additional content that is displayed when a user moves the pointer over a trigger or moves the keyboard focus to the trigger (for example, a pop-up) must remain visible to allow users time to read and interact with the content and must allow the user to move the pointer over the additional content.
Low vision users who magnify their screens often see only a small part of the screen at a time (their viewport). This means that the additional content may not be fully visible in the current viewport and users may need to move their mouse over the additional content to read it. Web authors should therefore ensue that additional content stays visible when the pointer moves away from the trigger to the (mostly adjacent) additional content. additional content should also be dismissible without moving the focus, so that users can read content covered by the additional content.
Examples
Example 1: Content preview for links
When hovering over or focusing on a link, a content preview for the link appears just above or below that link. Users can move the pointer over the additional content (pop-up) so that they can fully read the additional content. Pressing the Esc key dismisses (closes) the additional content.
HTML of example 1
<p>This is the <a class="a-and-tooltip" id="parent" href="index.html">trigger
<span id="popup" role="tooltip">And this additional text
gives additional context on the trigger term</span></a>.
Text and popup are <strong>in one link (a)</strong> element.</p>CSS of example 1
[role="tooltip"] {
display: none;
padding: 0.5em;
background:white;
color: black;
border:solid black 2px;
width:10em;
}
.a-and-tooltip {
position: relative;
}
[role="tooltip"] {
position: absolute;
left:0;
top:1em;
}JavaScript of example 1
// trigger and popup inside the same link
var parent = document.getElementById('parent');
parent.onmouseover = function() {
document.getElementById('popup').style.display = 'block';
}
parent.onmouseout = function() {
document.getElementById('popup').style.display = 'none';
}
parent.onfocus = function() {
document.getElementById('popup').style.display = 'block';
}
parent.onblur = function() {
document.getElementById('popup').style.display = 'none';
}
// hide when ESC is pressed
document.addEventListener('keydown', (e) => {
if ((e.keyCode || e.which) === 27)
document.getElementById('popup').style.display = 'none';
});