sticky-state/README.md

StickyState is a high performant module making native position:sticky statefull and polyfill the missing sticky browser feature

#StickyState

StickyState adds state to position:sticky elements and also polyfills the missing native sticky feature.

Dependency free, pure Javascript for IE9+.

Today's browsers do not all support the position:sticky feature (which by the way is being used (polyfilled) on pretty much every site you visit) - moreover the native supported feature itself comes without a readable state. Something like `a:hover => div:sticky` to add different styles to the element in its sticky state - or to read the state if needed in JavaScript. 

Unlike almost all polyfills you can find in the wild, StickyState is highly performant. The calculations are reduced to a minimum by persisting several attributes.

In some cases you also need to know in which direction the user scrolls - for example if you want to hide a sticky header when the user scrolls up. if you set the scrollClass property of the options StickyState will add your choosen classNames to the element when it is sticky and scrolling.

As a standalone Library its 6.75kb gzipped. 

### Dependencies
none!

### Browser support
IE >= 9, *

<br/>

### Install
```
npm install sticky-state
```

<br/>

### Demo
#### all you can eat
https://rawgit.com/soenkekluth/sticky-state/master/examples/index.html

#### headroom style
https://rawgit.com/soenkekluth/sticky-state/master/examples/headroom.html

#### simple
https://rawgit.com/soenkekluth/sticky-state/master/examples/simple.html

<br/>

### css
Your css should contain the following lines: 
(you can specify the classNames in js)
https://github.com/soenkekluth/sticky-state/blob/master/dist/sticky-state.css
```css
.sticky {
  position: -webkit-sticky;
  position: sticky;
}

.sticky.sticky-fixed.is-sticky {
  position: fixed;
  -webkit-backface-visibility: hidden;
  -moz-backface-visibility: hidden;
  backface-visibility: hidden;
}

.sticky.sticky-fixed.is-sticky:not([style*="margin-top"]) {
  margin-top: 0 !important;
}
.sticky.sticky-fixed.is-sticky:not([style*="margin-bottom"]) {
  margin-bottom: 0 !important;
}

.sticky.sticky-fixed.is-absolute{
  position: absolute;
}

```
<br/>

### js
```javascript
var StickyState = require('sticky-state');
new StickyState(document.querySelectorAll('.sticky'));
//  all elements with class .sticky will have sticky state:
```

#### options
```javascript

var StickyState = require('sticky-state');

// the props you can set (except scrollClass this shows the default options):
var stickyOptions = {
  disabled:       false,
  className:      'sticky',
  stateClassName: 'is-sticky',
  fixedClass:     'sticky-fixed',
  wrapperClass:   'sticky-wrap',
  absoluteClass:  'is-absolute',
  // do only set the following option if you really need a class for the scroll direction on the element. else this could be heavy unnassesary dom manipulation 
  scrollClass:{
    down: 'sticky-scroll-down',
    up: 'sticky-scroll-up'
  }
};

// instantiate with options
var stickyElements = new StickyState(document.querySelectorAll('.sticky'), stickyOptions);

```

#### api / events
```javascript
var StickyState = require('sticky-state');
new StickyState(document.querySelectorAll('.sticky'))
  .on('sticky:on', function(e){console.log('sticky:on', e.target);})
  .on('sticky:off', function(e){console.log('sticky:off' ,e.target);});

```
<br/>

### React Component
https://github.com/soenkekluth/react-sticky-state