Text Highlighter

A pointer arrow draws a highlight box around a word when the text scrolls into view.

Add a "Pointer Highlight" effect to [where].
As the text scrolls into view, a box should draw itself around the key word from left to right while a small pointer arrow travels along its corner, smooth and steady, as if someone is marking the word by hand.
Draw it only once when it first comes into view without shifting the text, and show the finished box right away for users who prefer reduced motion.

An underline grows from one side or the centre under a link on hover.

Add an "Underline Draw" hover effect (also called animated underline or hover underline animation) to [where].
When the pointer is over the link, an underline should grow smoothly from left to right under the text, and shrink back when the pointer leaves: quick and subtle.
Keep the underline from shifting the surrounding layout, and show the same effect on keyboard focus.

A line slides in from the bottom or top edge into place to underline or overline the element.

Add an "Underline Reveal" hover effect (also called overline reveal or reveal) to [where].
A full-width line should slide up into place from just below the bottom edge while the pointer is over the element, and slide back down out of view when it leaves: quick and smooth.
Clip the line at the edge so it appears by sliding rather than fading or growing, and show the same effect on keyboard focus.

An outlined word gets filled or lit by a gradient that follows the pointer or sweeps across.

Add a "Text Hover Effect" (also called text fill on hover or gradient outline text hover) to [where].
The word should start as an outline, and while the pointer is over it a solid fill should sweep in smoothly from left to right, then draw back out when the pointer leaves.
Keep the outlined word readable before the fill, and show the same effect on keyboard focus.

Text follows a curved path and travels along it as the user scrolls.

Add a "Text Path Scroll" effect (also called text path curve scroll animation) to [where].
The text should sit on a curved line and glide along it as the user scrolls, moving forward when scrolling down and back when scrolling up.
Tie the movement directly to the scroll position without lag, and keep the text readable as plain text for screen readers.

A word is duplicated into many stacked copies that shift with scroll.

Add a "Text Repetition" effect (also called repeated text scroll) to [where].
A word should be copied into a stack of fainter outline copies that spread out from behind it as the user scrolls, and fold back together when scrolling up.
Tie the spread directly to the scroll position, and hide the extra copies from screen readers so the word is read only once.