A function that allows a chrome extension to create a Facebook send message window with a pre-filled message, logging that message to the extension's console.

chromeExtensionFacebookSend.js

const sendMessage = (recipientID, link, message) => {
  const url = ("http://www.facebook.com/dialog/send?" +
               "app_id=" + appId +
               "&link=" + encodeURI(link) +
               "&to=" + recipientID +
               "&display=popup" +
               "&redirect_uri=" + encodeURI(link));
  chrome.tabs.create({ url }, (tab) => {
    const msg_val = 'document.querySelector("#feedform_user_message").value';
    chrome.tabs.executeScript(tab.id, {
      code: (msg_val + ' = decodeURI("' + encodeURI(message) + '");' + msg_val),
      runAt: 'document_end'
    }, (results) => console.log("From " + msg_val, results));
  });
};