/react-visibility-sensor

Sensor component for React that notifies you when it goes in or out of the window viewport.

Primary LanguageJavaScriptMIT LicenseMIT

React Visibility Sensor

Build Status

Sensor component for React that notifies you when it goes in or out of the window viewport.

Install

npm install react-visibility-sensor

Including the script directly

Useful if you want to use with bower, or in a plain old <script> tag.

In this case, make sure that React and ReactDOM are already loaded and globally accessible.

Take a look at the umd example to see this in action

Example

View the example

To run the example locally:

  • npm run build-example
  • open example/index.html in a browser

General usage goes something like:

function render () {
  var VisibilitySensor = require('react-visibility-sensor');

  var onChange = function (isVisible) {
    console.log('Element is now %s', isVisible ? 'visible' : 'hidden');
  };

  return (
    <VisibilitySensor onChange={onChange} />
  );
}

You can also pass a child function, which can be convenient if you don't need to store the visibility anywhere:

return (
  <VisibilitySensor>
    {({isVisible}) =>
      <div>I am {isVisible ? 'visible' : 'invisible'}</div>
    }
  </VisibilitySensor>
);

Props

  • onChange: callback for whenever the element changes from being within the window viewport or not. Function is called with 1 argument (isVisible: boolean)
  • active: (default true) boolean flag for enabling / disabling the sensor. When active !== true the sensor will not fire the onChange callback.
  • partialVisibility: (default false) consider element visible if only part of it is visible. Also possible values are - 'top', 'right', 'bottom', 'left' - in case it's needed to detect when one of these become visible explicitly.
  • offset: (default {}) with offset you can define amount of px from one side when the visibility should already change. So in example setting offset={{top:10}} means that the visibility changes hidden when there is less than 10px to top of the viewport. Offset works along with partialVisibility
  • minTopValue: (default 0) consider element visible if only part of it is visible and a minimum amount of pixels could be set, so if at least 100px are in viewport, we mark element as visible.
  • intervalCheck: (default true) when this is true, it gives you the possibility to check if the element is in view even if it wasn't because of a user scroll
  • intervalDelay: (default 100) integer, number of milliseconds between checking the element's position in relation the the window viewport. Making this number too low will have a negative impact on performance.
  • scrollCheck: (default: false) by making this true, the scroll listener is enabled.
  • scrollDelay: (default: 250) is the debounce rate at which the check is triggered. Ex: 250ms after the user stopped scrolling.
  • scrollThrottle: (default: -1) by specifying a value > -1, you are enabling throttle instead of the delay to trigger checks on scroll event. Throttle supercedes delay.
  • resizeCheck: (default: false) by making this true, the resize listener is enabled. Resize listener only listens to the window.
  • resizeDelay: (default: 250) is the debounce rate at which the check is triggered. Ex: 250ms after the user stopped resizing.
  • resizeThrottle: (default: -1) by specifying a value > -1, you are enabling throttle instead of the delay to trigger checks on resize event. Throttle supercedes delay.
  • containment: (optional) element to use as a viewport when checking visibility. Default behaviour is to use the browser window as viewport.
  • delayedCall: (default false) if is set to true, wont execute on page load ( prevents react apps triggering elements as visible before styles are loaded )
  • children: can be a React element or a function. If you provide a function, it will be called with 1 argument {isVisible: ?boolean, visibilityRect: Object}

It's possible to use both intervalCheck and scrollCheck together. This means you can detect most visibility changes quickly with scrollCheck, and an intervalCheck with a higher intervalDelay will act as a fallback for other visibility events, such as resize of a container.

Thanks

Special thanks to contributors:

  • Andrew Hong
  • Oleg Slobodskoi
  • EugeneHlushko
  • Stefan B
  • Radu-Sebastian Amarie
  • Roope Merikukka
  • Christian Davis
  • Anton Fedchenko
  • Mateusz Burzyński
  • Zak Linder
  • Andarist
  • Andy Edwards
  • Bram Schulting
  • Dan Abramov
  • Daniel Stefanovic
  • Eric Bower
  • Julien Bachmann
  • Neehar Venugopal
  • Rubens Mariuzzo
  • Tim Tyrrell

License

MIT