How to update a date field using JS

I’m trying to create a record that contains a date field, and failing badly! Nothing is getting written for the date at all.

The code is catching the submit action on one record, and creating a new record in another table that uses the date field from the submitted record.

Here’s the (minimal) code:

$(document).on('knack-form-submit.view_19', function(event, view, record) {
	var user = Knack.getUserAttributes().id;
    if (user) {
      console.log("Close Date: %s", record.field_78);
      console.log("Close Date raw: %o", record.field_78_raw);
          url: '',
          type: 'POST',
          async: false,
          headers: {'X-Knack-Application-Id': 'XXXXXXXXXXXXXXXXX', 'X-Knack-REST-API-Key': 'knack', 'Authorization': Knack.getUserToken(), 'Content-Type': 'application/json'},
          data: JSON.stringify({'field_95':}),
          success: function (response) {
            console.log("Record created");
          error: function(response){

field_95 is a date field in the destination record, field 78 in the source record, both formatted as mm/dd/yyyy.

I’ve tried all of the following, all with no luck:

data: JSON.stringify({'field_95': record.field_78})
data: JSON.stringify({'field_95': record.field_78_raw})
data: JSON.stringify({'field_95':})
data: JSON.stringify({'field_95': {'date':})

The console shows what I would expect:

Close Date: 11/30/2021
VM16773:12 Close Date raw: {date: “11/30/2021”, date_formatted: “11/30/2021”, hours: “12”, minutes: “00”, am_pm: “AM”, …}

Any suggestions?

OK, turns out it was a really dumb error on my part elsewhere!

For reference, the correct syntax is the very simple
data: JSON.stringify({'field_95': record.field_78})