::highlight()
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The ::highlight()
CSS pseudo-element applies styles to a custom highlight.
A custom highlight is a collection of Range
objects and is registered on a webpage using the HighlightRegistry
.
Allowable properties
Only certain CSS properties can be used with ::highlight()
:
color
background-color
text-decoration
and its associated propertiestext-shadow
-webkit-text-stroke-color
,-webkit-text-fill-color
and-webkit-text-stroke-width
In particular, background-image
is ignored.
Syntax
::highlight(custom-highlight-name)
Examples
Highlighting characters
HTML
html
<p id="rainbow-text">CSS Custom Highlight API rainbow</p>
CSS
css
#rainbow-text {
font-family: monospace;
font-size: 1.5rem;
}
::highlight(rainbow-color-1) {
color: #ad26ad;
text-decoration: underline;
}
::highlight(rainbow-color-2) {
color: #5d0a99;
text-decoration: underline;
}
::highlight(rainbow-color-3) {
color: #0000ff;
text-decoration: underline;
}
::highlight(rainbow-color-4) {
color: #07c607;
text-decoration: underline;
}
::highlight(rainbow-color-5) {
color: #b3b308;
text-decoration: underline;
}
::highlight(rainbow-color-6) {
color: #ffa500;
text-decoration: underline;
}
::highlight(rainbow-color-7) {
color: #ff0000;
text-decoration: underline;
}
JavaScript
js
const textNode = document.getElementById("rainbow-text").firstChild;
if (!CSS.highlights) {
textNode.textContent =
"The CSS Custom Highlight API is not supported in this browser!";
}
// Create and register highlights for each color in the rainbow.
const highlights = [];
for (let i = 0; i < 7; i++) {
// Create a new highlight for this color.
const colorHighlight = new Highlight();
highlights.push(colorHighlight);
// Register this highlight under a custom name.
CSS.highlights.set(`rainbow-color-${i + 1}`, colorHighlight);
}
// Iterate over the text, character by character.
for (let i = 0; i < textNode.textContent.length; i++) {
// Create a new range just for this character.
const range = new Range();
range.setStart(textNode, i);
range.setEnd(textNode, i + 1);
// Add the range to the next available highlight,
// looping back to the first one once we've reached the 7th.
highlights[i % 7].add(range);
}
Result
Specifications
Specification |
---|
CSS Custom Highlight API Module Level 1 # custom-highlight-pseudo |
Browser compatibility
BCD tables only load in the browser