Use this to wait for an element to be rendered before continuing

waitForElement.js

// from https://stackoverflow.com/a/61511955/1513051 
function waitForElement(selector) {
    return new Promise(resolve => {
        if (document.querySelector(selector)) {
            return resolve(document.querySelector(selector));
        }

        const observer = new MutationObserver(mutations => {
            if (document.querySelector(selector)) {
                resolve(document.querySelector(selector));
                observer.disconnect();
            }
        });

        observer.observe(document.body, {
            childList: true,
            subtree: true
        });
    });
}


/*
Ex. 
const el = await waitForElement('.some-classname')
// do something with el
*/