Testcafe - retreive data from Request Payload

I need to retrieve information from a POST call using Testcafe.

What I need to do manually is:

1. open developers tool in Chrome,
2. catch a traffic and filter by specific request name,
3. go to Headers -> Request Payload

In the Request Payload I need to check flag of isMode.

{timestamp: 9017205278, master: "s",…}
> ads: [{format: 19521, tag: "19521", target: "", isMode: false},…]
   > 0: {format: 19521, tag: "19521", target: "", isMode: false}
        format: 19521
        isMode: false
   > 1: {format: 19522, tag: "19522", target: "", isMode: true}
> appName: ""
> master: "s"
> screen: {height: 1080, width: 1920}
> timestamp: 9017205278

I am able to get info from requests using this method https://devexpress.github.io/testcafe/documentation/guides/advanced-guides/intercept-http-requests.html#log-http-requests

but to be honest I have no idea how to retreive info like in this example as above.