Implementing Search Feature In SUSI Web Chat

SUSI WebChat now has a search feature. Users now have an option to filter or find messages. The user can enter a keyword or phrase in the search field and all the matched messages are highlighted with the given keyword and the user can then navigate through the results.

Lets visit SUSI WebChat and try it out.

  1. Clicking on the search icon on the top right corner of the chat app screen, we’ll see a search field expand to the left from the search icon.
  2. Type any word or phrase and you see that all the matches are highlighted in yellow and the currently focused message is highlighted in orange
  3. We can use the up and down arrows to navigate between previous and recent messages containing the search string.
  4. We can also choose to search case sensitively using the drop down provided by clicking on the vertical dots icon to the right of the search component.
  5. Click on the `X` icon or the search icon to exit from the search mode. We again see that the search field contracts to the right, back to its initial state as a search icon.

How does the search feature work?

We first make our search component with a search field, navigation arrow icon buttons and exit icon button. We then listen to input changes in our search field using onChange function, and on input change, we collect the search string and iterate through all the existing messages checking if the message contains the search string or not, and if present, we mark that message before passing it to MessageListItem to render the message.

let match = msgText.indexOf(matchString);

  if (match !== -1) {
    msgCopy.mark = {
    matchText: matchString,
    isCaseSensitive: isCaseSensitive
  };

}

We alse need to pass the message ID of the currently focused message to MessageListItem as we need to identify that message to highlight it in orange instead of yellow differentiating between all matches and the current match.

function getMessageListItem(messages, markID) {
  if(markID){
    return messages.map((message) => {
      return (
        <MessageListItem
          key={message.id}
          message={message}
          markID={markID}
        />
      );
    });
  }
}

We also store the indices of the messages marked in the MessageSection Component state which is later used to iterate through the highlighted results.

searchTextChanged = (event) => {

  let matchString = event.target.value;
  let messages = this.state.messages;
  let markingData = searchMsgs(messages, matchString,
    this.state.searchState.caseSensitive);

  if(matchString){

    let searchState = {
      markedMsgs: markingData.allmsgs,
      markedIDs: markingData.markedIDs,
      markedIndices: markingData.markedIndices,
      scrollLimit: markingData.markedIDs.length,
      scrollIndex: 0,
      scrollID: markingData.markedIDs[0],
      caseSensitive: this.state.searchState.caseSensitive,
      open: false,
      searchText: matchString
    };

    this.setState({
      searchState: searchState
    });

  }
}

After marking the matched messages with the search string, we pass the messages array into MessageListItem Component where the messages are processed and rendered. Here, we check if the message being received from MessageSection is marked or not and if marked, we then highlight the message. To highlight all occurrences of the search string in the message text, I used a module called react-text-highlight.

import TextHighlight from 'react-text-highlight';

if(this.props.message.id === markMsgID){
  markedText.push(
    <TextHighlight
      key={key}
      highlight={matchString}
      text={part}
      markTag='em'
      caseSensitive={isCaseSensitive}
    />
  );
}
else{
  markedText.push(
    <TextHighlight
      key={key}
      highlight={matchString}
      text={part}
      caseSensitive={isCaseSensitive}/>
  );
}

Here, we are using the message ID of the currently focused message, sent as props to MessageListItem to identify the currently focused message and highlight it specifically in orange instead of the default yellow color for all other matches.

I used ‘em’ tag to emphasise the currently highlighted message and colored it orange using CSS attributes.

em{
  background-color: orange;
}

We next need to add functionality to navigate through the matched results. The arrow buttons are used to navigate. We stored all the marked messages in the MessageSection state as `markedIDs` and their corresponding indices as `markedIndices`. Using the length of this array, we get the `scrollLimit` i.e we know the bounds to apply while navigating through the search results.

On clicking the up or down arrows, we update the currently highlighted message through `scrollID` and `scrollIndex`, and also check for bounds using `scrollLimit`  in the searchState. Once these are updated, the chat app must automatically scroll to the new currently highlighted message. Since findDOMNode is being deprecated, I used the custom scrollbar to find the node of the currently highlighted message without using findDOMNode. The custom scrollbar was implemented using the module react-custom-scrollbars. Once the node is found, we use the inbuilt HTML DOM method, scrollIntoView()  to automatically scroll to that message.

if(this.state.search){
  if (this.state.searchState.scrollIndex === -1
      || this.state.searchState.scrollIndex === null) {
      this._scrollToBottom();
  }
  else {
    let markedIDs = this.state.searchState.markedIDs;
    let markedIndices = this.state.searchState.markedIndices;
    let limit = this.state.searchState.scrollLimit;
    let ul = this.messageList;

    if (markedIDs && ul && limit > 0) {
      let currentID = markedIndices[this.state.searchState.scrollIndex];
      this.scrollarea.view.childNodes[currentID].scrollIntoView();
    }
  }
}

Let us now see how the search field was animated. I used a CSS transition property along width to get the search field animation to work. This gives the animation when there is a change of width for the search field. I fixed the width to be zero when the search mode is not activated, so only the search icon is displayed. When the search mode is activated i.e the user clicks on the search field, I fixed the width as 125px. Since the width has changed, the increase in width is displayed as an expanding animation due to the CSS transition property.

const animationStyle = {
  transition: 'width 0.75s cubic-bezier(0.000, 0.795, 0.000, 1.000)'
};

const baseStyles = {
  open: { width: 125 },
  closed: { width: 0 },
}

We also have a case sensitive option which is displayed on clicking the rightmost button i.e the three vertical dots button. We can toggle between case sensitive option, whose value is stored in MessageSection searchState and is passed along with the messages to MessageListItem where it is used by react-text-highlight to highlight text accordingly and render the highlighted messages.

This is how the search feature was implemented in SUSI WebChat. You can find the complete code at SUSI WebChat.

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