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https://github.com/estrattonbailey/overunder

Tiny waypoint library.
https://github.com/estrattonbailey/overunder

emits-events listeners position waypoint-library

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Tiny waypoint library.

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# overunder
Tiny waypoint library. **750 bytes gzipped.**

## Features
1. Supports both x and y axis
2. Accepts both integer values and DOM nodes
3. Only one `scroll` and one `resize` listener

# Usage
```javascript
import overunder from 'overunder'

const scroller = overunder({
y: 1000
})

scroller.on('y over', () => {
console.log('user scrolled over 1000px')
})

scroller.update()
```
```javascript
import overunder from 'overunder'

const scroller = overunder({
y: document.getElementById('lazyImg')
})

scroller.on('y over', () => {
console.log('#lazyImg is visible')
})

scroller.update()
```
```javascript
import overunder from 'overunder'

const scroller = overunder({
x: 900
})

scroller.on('x under', () => {
console.log('viewport is < 900px wide')
})

scroller.update()
```
```javascript
import overunder from 'overunder'

const scroller = overunder({
x: 900,
x2: 1200
})

scroller.on('x between', () => {
console.log('viewport is between 900px and 1200px wide')
})

scroller.update()
```
```javascript
import overunder from 'overunder'

const scroller = overunder({
x: 900,
y: document.getElementById('hideNavTrigger')
})

scroller.on('x under', () => {
scroller.update({
y: document.getElementById('hideNavTrigger2')
})
})
scroller.on('x over', () => {
scroller.update({
y: document.getElementById('hideNavTrigger')
})
})

scroller.update()
```

## Events
`overunder` emits events depending on what waypoints you pass to it. They follow
the same pattern: ` `. Given an `x` and `y` value, `overunder`
will emit the following events.
- `x over`
- `x under`
- `y over`
- `y under`

Pass a second value for each and `overunder` will emit `between` event:
- `x between`
- `y between`

### Subscribing to events
```javascript
const listener = scroll.on('y over', () => {})

listener() // destroy listener
```

## API
### update([options])
Checks position and fires applicable listeners.
```javascript
scroller.update()
```
Pass an optional options object to update waypoint values.
```javascript
scroller.update({
x: 1000
})
```

## License
MIT License © [Eric Bailey](https://estrattonbailey.com)