To avoid displaying the text using the displayText_() function, create a new function that sends the JSON data to your desired destination.
var NEW_JSON_DESTINATION_URL = 'http://requestb.in/abc12345';
function postJsonData_(jsonData) {
var requestOptions = {
"contentType":"application/json",
"method" : "post",
"payload" : jsonData
};
UrlFetchApp.fetch(NEW_JSON_DESTINATION_URL, requestOptions);
}
If you still wish to show the text popup, simply execute this function before calling displayText_().
If your intention is to send this data via POST method, refer to the "method" section and examples in the following documentation:
https://developers.google.com/apps-script/reference/url-fetch/url-fetch-app