vue-visibility-sensor

Vue Visibility Sensor
====

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

Inspired by React Visibility Sensor

Install
----

npm install vue-visibility-sensor

This component is recommended to use in Vue-cli SPA project. Because it doesn't build as any bundle like AMD or UMD.

It's just a single file component.

Example
----

Try building an example yourself locally, here's another:

View the example

To run the example locally:

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

General usage goes something like:

``js
const VisibilitySensor = require('vue-visibility-sensor');

// with children
new Vue({
components: {
VisibilitySensor,
},
template:

// without children
new Vue({
components: {
VisibilitySensor,
},
template:


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

Event
----

- change: the event name emitted from sensor whenever the element changes from being within the window viewport or not. Event name is 'change', all in lower case. Function is called with 1 argument (isVisible: boolean)

Props
----

|Name|Default Value|Description|
|:-:|:-:|:-|
|active|true| boolean flag for enabling / disabling the sensor. When active !== true the sensor will not fire the onChange callback.|
|partialVisibility|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|{}| 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|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|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|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|false| by making this true, the scroll listener is enabled.|
|scrollDelay|250| the debounce rate at which the check is triggered. Ex: 250ms after the user stopped scrolling.|
|scrollThrottle|-1| by specifying a value > -1, you are enabling throttle instead of the delay to trigger checks on scroll event. Throttle supercedes delay.|
|resizeCheck|false| by making this true, the resize listener is enabled. Resize listener only listens to the window.|
|resizeDelay|250| is the debounce rate at which the check is triggered. Ex: 250ms after the user stopped resizing.|
|resizeThrottle|-1| by specifying a value > -1, you are enabling throttle instead of the delay to trigger checks on resize event. Throttle supercedes delay.|
|delayedCall|false| if is set to true, wont execute on page load ( prevents react apps triggering elements as visible before styles are loaded )|
|containment| window | element to use as a viewport when checking visibility. Default behaviour is to use the browser window as viewport.|
|children| | can be a template or vue component|

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 Josh Johnston

License
----

MIT