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 ✔

size

js ~5kb
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 and rpi.bundle.css in the html page
Apply the markup structure
Init the library with JS

html structure

<head>
  ...
  <link rel="stylesheet" href="rpi.bundle.css">
  ...
</head>
<body>
  <!-- library markup -->
  <div id="rpi-progress-bar-container" 
    class="rpi-progress-bar-container" 
    role="progressbar" 
    aria-valuemin="0" 
    aria-valuemax="100"
    aria-valuenow="0">
      <div class="rpi-progress-bar-container__position" aria-hidden="true"></div>
      <div class="rpi-progress-bar-container__percentage"></div>
  </div>
  <!-- end library markup -->
  
       ...          
       
       <script src="rpi.bundle.js"></script> <!-- library -->
       <script>new ReadingPositionIndicator().init();</script> <!-- usage -->
 </body>

minimum markup required

<div id="rpi-progress-bar-container" class="rpi-progress-bar-container">
      <div class="rpi-progress-bar-container__position"></div>
      <div class="rpi-progress-bar-container__percentage"></div>
</div>

configuration example

var rpi = new ReadingPositionIndicator({
          color: 'navyblue', // progress bar color
          percentage: {
            show: true,
            opacity: .3,
            color: '#000',
          },
        }).init();
//rpi.destroy(); // use when to be removed

how does it work?

It uses JS to calculate the document height and the viewport height to calculate the current position. The calculation is updated on scroll and resize event and the information is updated to the markup.

license

MIT License: http://opensource.org/licenses/MIT

FAQs

What is reading-position-indicator?

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Is reading-position-indicator well maintained?

Package last updated on 10 Feb 2017

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Install

reading-position-indicator