I have two iframe and one service worker

<iframe></iframe>
<iframe></iframe>

As a service worker I am at the destination

service worker

    let iframeClientId = new Map()
    let destination = event.request.destination;
......

    if(destination === 'iframe') {
        if(!iframeClientId.has(event.resultingClientId)) {
            iframeClientId.set(event.resultingClientId, {
                pathname: pathnameIframe
            })
        }

        if(!url.pathname.includes('index.sw.html')) {
            isSw = true
        }
    }

......

There are redirects to HTML pages in the iframe.

When the transfer is made to learn.html event.resultingClientId is changed.

At this moment, I cannot understand how the iframe created output

I entered all the data by question, but not here, how to divide iframe.

Is there any possibility to access how the iframe contains
event.resultingClientId ?