How to use the xregexp.cache function in xregexp

output = output.replace(//g, '>');
    output = output.replace(/'/g, ''');
    output = output.replace(/"/g, '"');

    return output;
}

// Copied from our fork of commonmark.js
var emailAlphaNumericChars = '\\p{L}\\p{Nd}';
var emailSpecialCharacters = '!#$%&\'*+\\-\\/=?^_`{|}~';
var emailRestrictedSpecialCharacters = '\\s(),:;<>@\\[\\]';
var emailValidCharacters = emailAlphaNumericChars + emailSpecialCharacters;
var emailValidRestrictedCharacters = emailValidCharacters + emailRestrictedSpecialCharacters;
var emailStartPattern = '(?:[' + emailValidCharacters + '](?:[' + emailValidCharacters + ']|\\.(?!\\.|@))*|\\"[' + emailValidRestrictedCharacters + '.]+\\")@';
var reEmail = XRegExp.cache('(^|[^\\pL\\d])(' + emailStartPattern + '[\\pL\\d.\\-]+[.]\\pL{2,4}(?=$|[^\\p{L}]))', 'g');

// Convert emails into tokens
function autolinkEmails(text, tokens) {
    function replaceEmailWithToken(fullMatch, prefix, email) {
        const index = tokens.size;
        const alias = `$MM_EMAIL${index}$`;

        tokens.set(alias, {
            value: `<a href="mailto:${email}" class="theme">${email}</a>`,
            originalText: email,
        });

        return prefix + alias;
    }

    let output = text;

if (originalText.length < minimumHashtagLength + 1) {
            // too short to be a hashtag
            return fullMatch;
        }

        tokens.set(alias, {
            value: `<a data-hashtag="${originalText}" href="#" class="mention-link">${originalText}</a>`,
            originalText,
            hashtag: originalText.substring(1),
        });

        return prefix + alias;
    }

    return output.replace(XRegExp.cache('(^|\\W)(#\\pL[\\pL\\d\\-_.]*[\\pL\\d])', 'g'), replaceHashtagWithToken);
}

handlePretextChanged(pretext, resultCallback) {
        const captured = XRegExp.cache('(?:^|\\W)@([\\pL\\d\\-_.]*)$', 'i').exec(pretext.toLowerCase());
        if (!captured) {
            return false;
        }

        const prefix = captured[1];

        this.startNewRequest(prefix);
        this.updateMatches(resultCallback, this.users());

        // If we haven't gotten server-side results in 500 ms, add the loading indicator.
        let showLoadingIndicator = setTimeout(() => {
            if (this.shouldCancelDispatch(prefix)) {
                return;
            }

            this.updateMatches(resultCallback, this.users().concat([{

}

        tokens.set(alias, {
            value: `<a data-hashtag="${originalText}" href="#" class="mention-link">${originalText}</a>`,
            originalText,
            hashtag: originalText.substring(1),
        });

        return prefix + alias;
    }

    return output.replace(XRegExp.cache('(^|\\W)(#\\pL[\\pL\\d\\-_.]*[\\pL\\d])', 'g'), replaceHashtagWithToken);
}

const puncStart = XRegExp.cache('^[^\\pL\\d\\s#]+');
const puncEnd = XRegExp.cache('[^\\pL\\d\\s]+$');

function parseSearchTerms(searchTerm) {
    let terms = [];

    let termString = searchTerm;

    while (termString) {
        let captured;

        // check for a quoted string
        captured = (/^"([^"]*)"/).exec(termString);
        if (captured) {
            termString = termString.substring(captured[0].length);

            if (captured[1].length &gt; 0) {
                terms.push(captured[1]);

return fullMatch;
        }

        tokens.set(alias, {
            value: `<a data-hashtag="${originalText}" href="#" class="mention-link">${originalText}</a>`,
            originalText,
            hashtag: originalText.substring(1),
        });

        return prefix + alias;
    }

    return output.replace(XRegExp.cache('(^|\\W)(#\\pL[\\pL\\d\\-_.]*[\\pL\\d])', 'g'), replaceHashtagWithToken);
}

const puncStart = XRegExp.cache('^[^\\pL\\d\\s#]+');
const puncEnd = XRegExp.cache('[^\\pL\\d\\s]+$');

function parseSearchTerms(searchTerm) {
    let terms = [];

    let termString = searchTerm;

    while (termString) {
        let captured;

        // check for a quoted string
        captured = (/^"([^"]*)"/).exec(termString);
        if (captured) {
            termString = termString.substring(captured[0].length);

            if (captured[1].length &gt; 0) {

let $
    try {
      $ = cheerio.load(body)
    } catch (e) {
      throw new Error('Error loading DOM', e)
    }
    const idRegex = 'station=(\\d*)'
    const titleRegex = '^(([\\p{L}0-9-]*[\\s-]?)*)\\s-'
    const stations = []
    const hrefs = $('.listtable td a:contains(\'A\')')

    for (let i = 0; i < hrefs.length; i++) {
      const elem = $(hrefs[i])
      // get the station title and id
      const titleMatch = xregexp.cache(titleRegex).exec(elem.attr('title'))
      const idMatch = xregexp.cache(idRegex).exec(elem.attr('href'))

      if (!idMatch || !titleMatch) {
        throw new Error('Parsing error -- Source is changed')
      }
      stations.push({
        name: titleMatch[1],
        id: idMatch[1],
      })
    }
    return res.cache(86400).json({ results: stations })
  })
})

// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

import XRegExp from 'xregexp';
import {getEmojiImageUrl} from 'mattermost-redux/utils/emoji_utils';
import emojiRegex from 'emoji-regex';

import {formatWithRenderer} from 'utils/markdown';
import {getEmojiMap} from 'selectors/emojis';
import store from 'stores/redux_store.jsx';

import * as Emoticons from './emoticons.jsx';
import * as Markdown from './markdown';

const punctuation = XRegExp.cache('[^\\pL\\d]');

const AT_MENTION_PATTERN = /\B@([a-z0-9.\-_]*)/gi;
const UNICODE_EMOJI_REGEX = emojiRegex();
const htmlEmojiPattern = /^<p>\s*(?:<img class="emoticon">]*&gt;|<span>]*&gt;[^&lt;]*&lt;\/span&gt;\s*|<span class="emoticon emoticon--unicode">[^&lt;]*&lt;\/span&gt;\s*)+&lt;\/p&gt;$/;

// pattern to detect the existence of a Chinese, Japanese, or Korean character in a string
// http://stackoverflow.com/questions/15033196/using-javascript-to-check-whether-a-string-contains-japanese-characters-includi
const cjkPattern = /[\u3000-\u303f\u3040-\u309f\u30a0-\u30ff\uff00-\uff9f\u4e00-\u9faf\u3400-\u4dbf\uac00-\ud7a3]/;

// Performs formatting of user posts including highlighting mentions and search terms and converting urls, hashtags,
// @mentions and ~channels to links by taking a user's message and returning a string of formatted html. Also takes
// a number of options as part of the second parameter:
// - searchTerm - If specified, this word is highlighted in the resulting html. Defaults to nothing.
// - searchMatches - If specified, an array of words that will be highlighted. Defaults to nothing. If both
//     this and searchTerm are specified, this takes precedence.
// - mentionHighlight - Specifies whether or not to highlight mentions of the current user. Defaults to true.</span></span></p>

let $
    try {
      $ = cheerio.load(body)
    } catch (e) {
      throw new Error('Error loading DOM', e)
    }
    const idRegex = 'station=(\\d*)'
    const titleRegex = '^(([\\p{L}0-9-]*[\\s-]?)*)\\s-'
    const stations = []
    const hrefs = $('.listtable td a:contains(\'A\')')

    for (let i = 0; i < hrefs.length; i++) {
      const elem = $(hrefs[i])
      // get the station title and id
      const titleMatch = xregexp.cache(titleRegex).exec(elem.attr('title'))
      const idMatch = xregexp.cache(idRegex).exec(elem.attr('href'))

      if (!idMatch || !titleMatch) {
        throw new Error('Parsing error -- Source is changed')
      }
      stations.push({
        name: titleMatch[1],
        id: idMatch[1],
      })
    }
    return res.cache(86400).json({ results: stations })
  })
})