Making a window pop under in chrome

Question

I have a button that needs to open a new window as a popup (under the parent page). In IE/Firefox, it works fine, but in chrome the popup appears over (on top of) the parent

Answer 1

This code works up to Chrome 65:

function just_open() {
    postMessage([...arguments]);
}
window.onmessage = function({data}){
    return open(...data);
}
function openunder() {
    just_open([...arguments]);
    window.open().close();
}

Where openunder is just like open() except:

• no return value
• No Chrome 65+, uses https://crbug.com/833148