const winHtml = `<button id="cool">Run code on other window</button>`;

const winUrl = URL.createObjectURL(
    new Blob([winHtml], { type: "text/html" })
);

const win = window.open(
    winUrl,
    "win",
    `width=800,height=400,screenX=200,screenY=200`
);

So I want to be able to run code from a new Window, opened with JS. This is not a new Browser tab, it is a new Browser window with html inserted. Is it possible to run code from it to the existing browser window?