POST data to a Google form with AJAX

Question

I am trying to post data to a from AJAX to a Google form, but even though it reports success with a statusCode of 0, the data never appears in the form:

var dat={ "entry.529474552" :"data1", "entry.1066559787": "name1"};
postToGoogle("1FAIpQLSf4w1OQGsIncaiqXlmfAl4jYSt-e4Zx3xVJa7Weob4LnQbRZQ",dat);

function postToGoogle(id, dat) {
    $.ajax({
        beforeSend: function (xhr) {
            xhr.setRequestHeader('Access-Control-Allow-Origin', 'chrome-extension://EXTENSION_ID');
            xhr.setRequestHeader('Access-Control-Allow-Methods', 'GET, POST, PUT');
            },
        url: "https://docs.google.com/forms/d/e/"+id+"/formResponse",
        data: dat, 
        type: "POST",  
        dataType: "xml",
        xhrFields: {  withCredentials: true },
        statusCode: {
            0:   function() {  console.log("OK") },
            200: function() {  console.log("error") },
            }
        });
    }

It generates a CORS error, but supposedly, the POST should go through anyway.

Answer 1

For those looking to do this as of April 2019

I was working on this today. The current answer is as follows:

Each field in the Google Form has a unique ID. In order to retrieve it, get a pre-filled link by filling out all relevant form fields you wish to programatically submit

Note: In order to ensure the URL is accessible without restriction, you'll also want to disable restriction to your domain only (for GSuite paying users)

Then, copy the link and paste in your browser. The URL has a base format as follows:

https://docs.google.com/forms/d/e/[FORMID]/formResponse

Each param is a key/value pair of type: entry.XXXXXX=value

The prefilled link will give you the value of XXXXX for each relevant field

Request must be made with following headers:

Method: GET

Content-Type: application/x-www-form-urlencoded

The final request looks like this

https://docs.google.com/forms/d/e/123332233bsj333/formResponse?entry.123456=value1&entry.2333442=value2&submit=Submit

Don't forget to append submit=Submit at the end of your request!