Export Google Messages content from the browser app.

export.js

function collateMessages(){
    const conversations = [];
    const msgRegex = /^(?<sender>[\w\W]+) said: (?<content>[\w\W]+) (?:Sent|Received) on (?<date>[\w\d\s,]+) at (?<time>[\d\:\s]+(?:AM|PM))\.\s?(?<status>Delivered\.)?\s?(?<meta>.*)$/;
    const msgEle = document.getElementsByTagName('mws-text-message-part');
    console.log(`fetching ${msgEle.length} messages`);
    for (var i = 0; i < msgEle.length; i++) { 
        const messageContent = msgEle.item(i).getAttribute('aria-label');
        const matches = messageContent.match(msgRegex);
        if (!matches?.groups) {
            console.warn('this message is special', messageContent);
        } else {
            const { sender, content, date, time, status, meta } = matches.groups;
            const t = new Date(`${date} ${time}`);
            
            conversations.push({
                sender, 
                content,
                time: t.toString(),
                timestamp: t.getTime(), 
                status, 
                meta,
            });
        }         
    }
    console.log(`got ${conversations.length} messages`);
    
    return conversations;
}


function downloadJSON(data, filename = 'data.json') {
    const jsonString = JSON.stringify(data);
    const blob = new Blob([jsonString], { type: 'application/json' });
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = filename;
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    URL.revokeObjectURL(url);
}

const msg = collateMessages();
downloadJSON(msg);