@mitter-io/react-scl v0.7.6

Mitter.io SCL (React)

The standard component library for ReactJS applications.

react-scl

• Function of the package

  This package is used for only for front-end UI in the web. Currently there are two components in this package MessageList and MessageWindow. Both components are powered by react-virtualized and is used for managing large message lists efficiently.

  MessageListManager uses MessageList to manage messages and MessageListManager is the component that is exposed to the user

  MessageWindowManager uses MessageWindow to manage messages and MessageWindowManager is the component that is exposed to the user

  Currently MessageListManager is deprecated , please use MessageWindowManager for finer control.

  The props for both of these components are listed below:

  Props for MessageListManager

  props	types
  messages	ChannelReferencingMessage[]
  onComponentMount?	() => void
  onComponentUpdate?	(currentProps: object, prevProps: object) => void
  producers	Producer[]	undefined . Array of producers which produces a view
  defaultView	(item: ChannelReferencingMessage) => ReactElement. A Default Component if none of the producers produce a view
  onEndCallback	() => void. Callback which gets called when the scroll bar reaches the top.
  loader	() => ReactElement. A spinner component to show the user when the messages are being fetched
  isLoading	boolean. To inform the component if the message fetching call is in flight. This tells the component to show the loader
  scrollToIndex?	number

  Props for MessageList

  props	types
  messages	ChannelReferencingMessage[]
  onEndCallback	() => void. Callback which gets called when the scroll bar reaches the top.
  getViewFromProducer	(item: ChannelReferencingMessage) => ReactElement
  loader	() => ReactElement. A spinner component to show the user when the messages are being fetched
  isLoading	boolean. To inform the component if the message fetching call is in flight. This tells the component to show the loader
  scrollToIndex?	number

  Props for MessageWindowManager

  props	types
  channelId	string
  messages	ChannelReferencingMessage[]
  producers	(item: ChannelReferencingMessage) => ReactElement
  fetchNewerMessages	(channelId: string, after?: string) => Promise<ChannelReferencingMessage[]>
  fetchOlderMessages	channelId: string, before?: string) => Promise<ChannelReferencingMessage[]>
  minRowHeight	number
  loader	ReactElement
  fetchThreshold?	number
  fixedHeight?	boolean
  mitter?	Mitter
  newMessagePayloadHook?	(message: ChannelReferencingMessage) => ChannelReferencingMessage
  scrollIndicator?	(unreadCount: number, onClick: () => void) => ReactElement

  Props for MessageWindow

  props	types
  initialMessages	ChannelReferencingMessage[]
  getViewFromProducer	(item: ChannelReferencingMessage) => ReactElement
  fetchNewerMessages	(channelId: string, after?: string) => Promise<ChannelReferencingMessage[]>
  fetchOlderMessages	channelId: string, before?: string) => Promise<ChannelReferencingMessage[]>
  minRowHeight	number
  loader	ReactElement
  fetchThreshold?	number
  fixedHeight	boolean
  scrollIndicator?	(unreadCount: number, onClick: () => void) => ReactElement

  MessageListManager

  MessageListManager is the component exposed to the user. It uses MessageList to manager messages and MessageList internally uses React-Virtualized. The props taken by the component is given above

  MessageList

  MessageList internally uses React-Virtualized. Please go through the API docs of React-Virtualized before going through this component. The props taken by this component is given above.

  An example of this implementation is at
  https://github.com/mitterio/mitter-web-starter/tree/with-scl

  MessageWindowManager

  MessageWindowManager is the component exposed to the user. It is complete different implementation of the MessageListManager.

  MessageWindow

  On Fist Load of the component

  This component takes in an initial set of messages(if the user has saved some messages in his local storage or any storage) and makes a call to get messages after the given set of messages from the user or makes a call to get the latest set if the user has not provided any initial set

  The component keeps fetching for messages till a scroll appears so that the window is scrollable. If the total number of messages in the channel fits in the window, the call returns an empty array the component terminates the fetching process and sets fetchTillScrollable to false

  On Scroll To Top and Scroll To End Callbacks are triggered when the user scrolls to both end. Scrolling to top triggers a fetchOlderMessages call and scrolling to the bottom triggers a fetchNewerMessages call.

  Deduping messages This component does perform a deduping operation on the initial messages that are given by the user and on the messages given by fetchOlderMessages and fetchNewerMessages

  Reason for taking channelId as a prop In a web.whatsapp style layout where the chat list is on the left side and the active chat is on the right side of the screen, passing the active channel Id to the component unmounts the MessageWindow and loads a new instance of the MessageWindow with new messages

  An example implementation of this component is given below

   <div style={{flex: 1, backgroundColor: '#f5f5f5'}}>
                      <MessageWindowManager
                          ref={this.msgManagerRef}
                          messages={this.props.queriedMessages || []} // initial messages from state containers ( redux or mobx) or from local storage
                          producers={[this.messageViewProducer]} // producers
                          defaultView={(message) => {
                              return <div
                                  style={{'borderTop': '1px solid black'}}>{message.textPayload}</div>
                          }}
                          fetchNewerMessages = {this.fetchNewerMessages}
                          fetchOlderMessages = {this.fetchOlderMessages}
                          loader={<LoaderForMsgFetch/>}
                          channelId = {this.queriedRandomChannelId}
                          minRowHeight={141}
                          fixedHeight={false}
                          newMessagePayloadHook = {channelReferencingMessageDecoder}
                          scrollIndicator={ScrollIndicator()}
                      />
                  </div>
              </div>

* Message View Producer Sample

this.messageViewProducer = createMessageViewProducer( (_message) => true, (message) => { return ( ) } )

fetchNewerMessages = (channelId: string, after?: string) => {

     /** SEND INFLIGHT HERE IF REQUIRED */
     if (after) {
         this.msgPaginationManager.after = after
     }
     
     return this.msgPaginationManager.nextPage()
         .then(messages => {
             return messages
         })
         .catch(() => {
             return []
         })

 }
 fetchOlderMessages = (channelId: string, before?: string) => {
     
     /** SEND INFLIGHT HERE IF REQUIRED */
     if (before) {
         this.msgPaginationManager.before = before
     }
     
     return this.msgPaginationManager.prevPage()
         .then(messages => {
             const messageListClone = messages.slice()
             return messages.reverse()
         })
         .catch(() => {
             return []
         })
 }

* example of a scroll indicator

import React from 'react'

type Props = { unReadCount : number onClick: () => void }

class ScrollHelper extends React.Component { constructor(props){ super(props) }

onClickScrollIndicator = () => {
    if(this.props.onClick) {
        this.props.onClick()
    }
}

render() {
    return(
        <div className= "mitter-scroll-indicator-container" onClick={this.onClickScrollIndicator}>
            <div className= "mitter-scroll-indicator">
                {
                    this.props.unReadCount  > 0 &&
                    <div className= "mitter-count-indicator">
                        {this.props.unReadCount}
                    </div>
                }

                <i className="material-icons mitter-down-arrow-indicator" >keyboard_arrow_down</i>
                <i className="material-icons mitter-down-arrow-indicator">keyboard_arrow_down</i>
            </div>
        </div>
    )
}

}

export default function ScrollIndicator() { return (unreadCount: number, onClick: () => void) => { return } }

* example of new messagePayload hook

export const channelReferencingMessageToLowerCase = (message: ChannelReferencingMessage): ChannelReferencingMessage => { message.textPayload = message.textPayload.toLowerCase() return message }