reading position indicator
Small mobile friendly reading position indicator library with no external dependencies.
demo
- https://codepen.io/kunukn/full/zNJqEE (version 1.0.3+)
- https://codepen.io/kunukn/full/ayeMZN/ (version 2.0.0+)
about
A position indicator at the top of the page to visually display how far you have scrolled on a webpage.
Build with focus on simplicity, performance and a11y. Using transform translate for best performance. rAF for throttling scroll update and debounce for resize update.
Aria tags are used to support screen readers.
The progress element <progress>
has not been used because the code gets messy with vendor prefixes and removing the default styles that comes with each browser. It gets even messier when fallback elements are added inside the progress element to support older browsers.
browser support
IE 10+ ✔ | Latest ✔ | Latest ✔ | Latest ✔ | Latest ✔ |
npm
https://www.npmjs.com/package/reading-position-indicator
size
- js
~6kb
- css
<1kb
test
Tested with latest Chrome, Safari, Firefox, Edge, IE10+, iOS7+, Android 4.3+
usage
Check the dist/index.html for inspiration.
- Add reference to
rpi.bundle.js
andrpi.bundle.css
in the html page - Apply the markup structure
- Init the library with JS
html structure
... ... <!-- library markup --> <!-- end library markup --> ... <!-- library --> <!-- usage -->
minimum markup required
configuration and usage example
var rpi;; // wait until DOM has fully rendered the article to get the calculations correct// rpi.destroy(); // use when to be removed// rpi.update(); // optional force update, example: DOM was updated and need to refresh the indicator
development
- git clone the project or download it
- npm install
- npm start
- open a browser and go to localhost:3333
build library into dist folder
- npm run build
how does it work?
It calculate heights for viewport, document and current scroll position. If rpiArea is used then it also uses getBoundingClientRect method to calculate dom element dimension. DOM updates are only applied if data has changed since last time. The calculation is updated on scroll and resize event and the information is updated to the DOM.
license
MIT License: http://opensource.org/licenses/MIT