React Visibility Sensor

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} />
  );
}

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={{direction: 'top', value:10}} means that the visibility changes hidden when there is less than 10px to top of the viewport. Setting offset automatically disables the 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) the default usage of Visibility Sensor is to trigger a check on user scrolling, by checking this as 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 1500) 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.
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 )

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:

License

MIT

eek / react-visibility-sensor Goto Github PK