Getting variable from webview to react native

I have a function in a webview which has response:

var respMsg = function(e) 
  {
    var respData = eval("(" + e.data + ")");
    document.getElementById("response").innerHTML = e.origin + " SENT " + " - " +
respData.responseCode + "-" + respData.dataKey + "-" + respData.errorMessage;
   document.getElementById("response").style.display = 'none';
  }

My question is: how to get for example respData.dataKey in a react native value so I can use it further (for example to get it and log its value)