autoscroll-react

Autoscroll a react component

Install

npm install --save autoscroll-react

What it does

This package exports a function that takes a React.Component and returns a React.PureComponent that renders the passed component without any additional markup. Whenever the wrapped component updates, it is scrolled to the bottom, unless the user has scrolled up. In addition (since 3.1.0), when the list is resized (when content is added), it will be scrolled in order to keep the user's original scroll position.

Usage

import React from 'react'
import autoscroll from 'autoscroll-react'

import Item from './Item'

class MyList extends React.Component {
    render(){
        const { items, ...props } = this.props
        return (
            <ul { ...props } >{ //  ⚠️ You MUST pass down props, otherwise the event listener will not be attached ⚠️
                items.map(
                    item => <Item 
                        key={ item.id } 
                        {...item}
                    />
                )
            }</ul>
        )
    }
}

export default autoscroll(MyList)

Then, in another file:

import React from 'react'
import MyList from './MyList'

export default ({ items, fetchMoreItems }) => <div>
    <MyList
        items={items} /* pass props directly to your component */
        onScrolledTop={e => fetchMoreItems()} /* add props to be intercepted by autoscroll */
        onScrolled={e => console.log('the list was scrolled')}
    />
    {/* ... */}
</div>

⚠️ caveats ⚠️

• You must Explicitly pass down props to the wrapped component. This is so an event listener can be attached. This means you can also pass down your own props to the wrapped component by passing them to the component returned by Autoscroll.
• The wrapped component must be a Class-based component, not a functional one, because Autoscroll uses a ref.
• This package is agnostic about any CSS you use. However, it assumes that you provide the adequate CSS to make the wrapped component have a scroll bar. (ie. overflow-y:scroll; and a set height)

options

Optional props:

• onScrolled: called whenever the list is scrolled. This is not an event listener.
• onScrolledTop: called when the list is scrolled to the top. Pass these props when rendering the wrapped list component.

autoscroll(Component, { isScrolledDownThreshold: 150 /*default*/})

The isScrolledDownThreshold option is used when determining whether the user has scrolled back to the bottom. If the element's scrollBottom is within isScrolledDownThresholdpx of the maximum scroll (scrollHeight), the component will scroll down on the next updates. This option exists because scrolling almost all the way down, but not entirely, can be interpreted as a sign that the user intends to see the bottom of the list. Set it to 0 to enforce scrolling all the way down.