FormData created from an existing form seems empty when I log it

Update: the XHR spec now includes several more functions to inspect FormData objects.

FireFox has supported the newer functions since v39.0, Chrome is slated to get support in v50. Not sure about other browsers.

var form = document.querySelector('form');
var formData = new FormData(form);

for (var [key, value] of formData.entries()) { 
  console.log(key, value);
}

//or

console.log(...formData)

I faced the same problem as well. I wasn't able to see on the console. You need to add the following to the ajax request, so the data will be sent

processData: false, contentType: false