To export whatsapp chat history (text only)

wa_chat_history_export.js

// This needs to be run on the browser console with the corresponding chat selected
// on Whatsapp Web. It also needs to have the whole conversation loaded.
// It copies the conversation to the clipboard, change it as needed.

conversation = '';

msgElements = document.querySelectorAll('div.copyable-text:not(._2_1wd)');

for (let msgElement of msgElements) {
  sender = msgElement.dataset.prePlainText;

  try {
    message = msgElement.querySelector('._3-8er.selectable-text.copyable-text span').innerText;
    completeMsg = sender + message;
    conversation += '\n' + completeMsg;
  } catch (error) {
  	continue;
  }
};

navigator.clipboard.writeText(conversation).then(function() {
  console.log('success');
}, function(err) {
  console.log('fail', err);
});