I want to pass imageArray[] along with a variable trackNo. The imageArray[] I can pass it fine with no problem. I'm just uncertain on how to append/include other variables to the FormData()
Online I only see examples of people passing only a file array to a php file and never with other information.
$('#ad_post_btn').click(function () {
    ad_errmsg = "";
    imageList = myImageList(); //my array of images imageList[]
    console.log(imageList); //display files in imageList[]
    var trackNo = Math.round(Math.random() * (100000 - 1) + 1); // random number
    console.log(trackNo); // shows the random generated number
    var data = new FormData(); 
    var dataString = 'trackno=' + trackNo; //the variable a want to pass along with the array
    for (var i = 0; i < imageList.length; i++) {
        data.append('images[]', imageList[i]); //where I store my image files, work fine
    }
    $.ajax({
        url: 'uploadimage.php',
        type: 'post',
        data: data,
        contentType: false,
        processData: false,
        success: function (data) {
            console.log(data);
        }
    });
I've tried
data: data,dataString ,
Thank you for your time
 
     
     
    