Is there a way to use MutationObserver JavaScript API in selenium

Question

I want to use MutationObserver on selenium to observe change of the element.

But following error have occured in observe():

Uncaught TypeError: Failed to execute 'observe' on 'MutationObserver': parameter 1 is not of type 'Node'.

I found information about the error. 'observe' on 'MutationObserver': parameter 1 is not of type 'Node'

According to above stackoverflow page, the error occure when invoke getElement... function before loading dom.

So I tried the way that wait until desired dom be visible, But the error occur.

I am using

• Python3.6.3
• selenium3.6
• Chrome 64.0.3248.0 (Official Build) canary.

Codes:

main.py:

from selenium import webdriver
from selenium.webdriver.chrome.options import Options
options = Options()
options.binary_location = '/Applications/Google Chrome Canary.app/Contents/MacOS/Google Chrome Canary'
options.add_experimental_option("detach", True)
#options.add_argument('--headless')
with open("execute_script.js") as f:
    script_source = f.read()

driver = webdriver.Chrome("./chromedriver", chrome_options=options)
driver.get("example.com/index.html")
close_icons = driver.find_elements_by_css_selector("i.CloseIcon")
if len(close_icons) >= 1:
    for v in close_icons:
        if v.is_displayed():
            v.click()
driver.execute_script(script_source)

execute_script.js: this script is loading as a execute script in main.py.

let body = document.getElementsByTagName("body")[0];
let script = document.createElement("script");
script.type = "application/javascript";

let str = `
let dom = document.getElementById('last-last');
function getDesiredDom() {
    dom = document.getElementById("last-last");
    if (!dom) {
        console.log("Desired dom does not exist yet")
        setTimeout(getDesiredDom, 500);
    }

}
getDesiredDom();
let ws = new WebSocket("ws://localhost:6788/");
ws.addEventListener("message", (message) => {
    console.log(message.data);
});
ws.onerror = (error) => console.log(error);

let observer_config = {childList: true, attributes: true, characterData: true};

let observer = new MutationObserver((mutation) => {
    for (v of mutation) {
        if (v.type === "childList") {
            for (x of v.addedNodes) {
                if (x.nodeName === '#text') {
                    console.log(x.nodeValue);
                    ws.send(x.nodeValue);
                }
            }
        }
    }
});
observer.observe(dom, observer_config);
`

script.innerHTML = str;
body.appendChild(script)