Slack Cache Export Snippet

slack_export.js

(function(){

const WORKSPACE_ID = 'YOUR-WORKSPACE-ID',
    DB_NAME = 'reduxPersistence',
    DB_VERSION = 2,
    STORE = 'reduxPersistenceStore';

function main(db) {
    if (WORKSPACE_ID === 'YOUR-WORKSPACE-ID') {
        alert('Please, change the WORKSPACE_ID');
        return;
    }

    let transaction = db.transaction([STORE], 'readonly');
    let objectStore = transaction.objectStore(STORE);
    
    let result = {};
    objectStore.openCursor().onsuccess = function (event) {
        let cursor = event.target.result;
        if (cursor) {
            if (cursor.key.includes(WORKSPACE_ID)) {
                result[cursor.key] = cursor.value;
            }
            cursor.continue();
        } else {
            showWidgets(result);
        }
    }
}

function showWidgets(db) {
    // Building blobs
    let full = JSON.stringify(db, null, 2);
    let blobs = {full: createTextBlob(full)};
    let dump = db[Object.keys(db)[0]];

    if (!dump.channels || !dump.members || !dump.messages) {
        console.log('RAW database:', db);
        alert('Error. See console output.');
        return;
    }
    
    let nestedObjFix = (o) => o.hasOwnProperty('internalUseOnlyByIdMap')
        ? o.internalUseOnlyByIdMap : o;

    let chats = nestedObjFix(dump.channels);
    let members = nestedObjFix(dump.members);

    for (let id in dump.messages) {
        let text = '';
        let chat = dump.messages[id];

        for (let ts in chat) {
            let message = chat[ts];
            let time = new Date(message.ts * 1000).toISOString();
            let sender = members[message.user] ? members[message.user].real_name : message.user;

            text += `${time} ${sender}:\n${message.text}\n${'_'.repeat(80)}\n\n`
        }

        blobs[id] = createTextBlob(text);
    }

    // Rendering widgets
    let root = window._slackExportRootElement = window._slackExportRootElement || document.createElement('div');
    root.innerHTML = `
        <style>
            .et_dd{padding:20px;margin:20px 0 20px 20px;width:200px;height:64px;}
            .et_dl{cursor:pointer;color:#fff;display:inline-block;text-align:center;background-color:green;padding:20px;margin: 20px 20px 20px -2px;width:200px;height:64px;}
        </style>`;

    document.body.insertBefore(root, document.body.firstChild);

    let downloadLink = html2Node('<a class="et_dl">Download</a>');
    let chatsDropdown = html2Node(`
        <select class="et_dd">
            <option data-href="${blobs.full}" data-download="indexedDB_${WORKSPACE_ID}.json">
                Full Backup as JSON
            </option>
        </select>`);

    chatsDropdown.addEventListener('change', function (e) {
        let selected = e.target[e.target.selectedIndex];
        downloadLink.setAttribute('href', selected.getAttribute('data-href'));
        downloadLink.setAttribute('download', selected.getAttribute('data-download'));
    });

    for (let id in chats) {
        let chat = chats[id];

        if (!dump.messages[id]) continue;
        
        chatsDropdown.appendChild(html2Node(`
            <option data-href="${blobs[id]}" data-download="chat_${chat.name}_${id}.txt" title="${chat.purpose.value || ''}">
                ${members[chat.user] ? members[chat.user].real_name : chat.name}
            </option>`));
    }

    root.appendChild(chatsDropdown);
    root.appendChild(downloadLink);
    window.scrollTo(0, 0);
}

function html2Node(html) {
    let template = document.createElement('template');
    html = html.trim();
    template.innerHTML = html;
    return template.content.firstChild;
}

function createTextBlob(text) {
     return window.URL.createObjectURL(new Blob([text], {'type': 'text/plain;charset=utf-8;'}));
}

let request = indexedDB.open(DB_NAME, DB_VERSION);
request.onsuccess = function () {
    main(request.result);
}
request.onerror = function (event) {
    console.log(request.errorCode);
}

})();

slack_export.md

Slack Cache Export Snippet

Tool for dumping local Slack cache. Works even after client access removal.

Steps to export

For Slack Application on Mac OS:

1. Open system console
2. Execute: export SLACK_DEVELOPER_MENU=true
3. Open Slack Application in the console: open /Applications/Slack.app
4. Press Cmd+Opt+I to open DevTools
5. Change the WORKSPACE_ID to the workspace ID of your company (see below how to find it)
6. Execute the script
7. Choose a chat in dropdown on the page top
8. Press Download

For Slack Web Client:

1. Open Slack in browser: https://app.slack.com/workspace-signin
2. Press Cmd+Opt+I to open DevTools
3. Change the WORKSPACE_ID to the workspace ID of your company (see below how to find it)
4. Execute the script
5. Choose a chat in dropdown on the page top
6. Press Download

Getting your company WORKSPACE_ID

Go to any Slack link in history of your browser, and you're going be redirected to URL like this:

https://app.slack.com/workspace-signin?redir=%2Fgantry%2Fauth%3Fcdn_fallback%3D1%26app%3Dclient%26lc%3D12347348%26return_to%3D%252Fclient%252FEEKV32DM%252F...

The text between ...return_to%3D%252Fclient%252F and %252F is your WORKSPACE_ID: EEKV32DM.