I have Web application A which opens web application B

such as on https://app1.com/index.html

<script>
window.open('https://app2.com/?data=XXX');
</script>

app2.com is opened by app1.com and app1 passes the data XXX to app2

then I want to return back the data from app B to app A with the variable YYY

such as window.open('https://app1.com/?data=YYY'), however it opens the another tab.

I want to return the data where existing appA

Is it possible or how can I do that?