feature-highlight

Feature Highlight is a lightweight TypeScript library for visually highlighting elements on a web page, perfect for onboarding, tutorials, or drawing user attention to features.

✨ Features

• ⚡ No dependencies — Works out of the box, no extra packages required
• 📦 Tiny footprint — Less than 2KB gzipped
• 📱 Responsive — Adapts to any screen size
• 🎨 Customizable — Easily adjust color, radius, border, and opacity
• 🚀 Fast & efficient — Minimal DOM manipulation for smooth performance
• 🛠️ TypeScript support — Strongly typed API for safer development

Install via npm:

npm install feature-highlight

Usage

Import the main highlight function and use it to highlight any element by selector or reference:

import { highlight, removeHighlight } from "feature-highlight";

highlight("#newFeatureButton", {
  color: "#388E3C",
  borderWidth: 3,
  borderColor: "#fff",
  opacity: 0.7,
});

const removeButton = document.querySelector("#removeHighlight");
removeButton.addEventListener("click", () => removeHighlight());

CSS variable

the library automatically set the following CSS variables to the root SVG element #fhRoot

--fh-radius // the radius of the highlight circle
--fh-left // left offset
--fh-top // top offset
--fh-right // right offset relative to the window width
--fh-bottom // bottom offset relative to the window height

Smooth transitions

You can make the transition smooth by adding the appropriate css transition rules, as an example:

#fhRoot circle {
  transition: 300ms linear all;
}

Bouncing example

You can benefit from the CSS variable properties to make a bouncing effect to the highlight circle

#fhRoot circle {
    animation: bounce 800ms alternate infinite;
}

@keyframes bounce {
    0% {
        r: var(--fh-radius);
    }
    100% {
        r: calc(var(--fh-radius) + 10px);
    }
}

API

highlight(elOrSelector, options)

• elOrSelector: string (CSS selector) or HTMLElement
• options: Partial
  • radius: number — Highlight circle radius (default: auto)
  • radiusPadding: number — adjust the radius size, useful only when the radius is automatically calculated (radius: undefined)
  • color: string — Highlight color (default: #388E3C)
  • borderWidth: number — Border width (default: 2)
  • borderColor: string — Border color (default: #fff)
  • opacity: number — Highlight opacity (default: 0.8)
  • cssClass: string — A css class set to the root svg element, useful for styling and animation

License

MIT