Q:

How to send additional data to jQuery File Upload Plugin?

This would seem stupid but i can't seem to understand the documentation.
I'm talking about This plugin for file upload.
Now according to the documentation there's an option :

formData
Additional form data to be sent along with the file uploads can be set using this
   option, which accepts an array of objects with name and value properties, a function 
   returning such an array, a FormData object (for XHR file uploads), or a simple object.
   The form of the first fileInput is given as parameter to the function.
Note: Additional form data is ignored when the multipart option is set to false.
Type: Array, Object, function or FormData Default: A function
  returning the form fields as serialized Array:
function (form) {
    return form.serializeArray();
}

Example:
[
      {
          name: 'a',
          value: 1
      },
      {
          name: 'b',
          value: 2
      } ]

Which i fail to understand what i'm suppoused to do with that.
This is how i initialize the plugin :
$('#add_image_upload').fileupload({
            dataType: 'json',
    sequentialUploads: true,
    formData : getDate
});

And this is my attempt to the function :
 function getDate(){

//if user didn't selected a date
if(!selectedDate || selectedDate=="undefined"){
selectedDate = "1/1/"+$('#timeline').html();
}
var date= new Array(selectedDate);
return date;
}

A:

try turning your data into in object - with what they showed in their example
$('#add_image_upload').fileupload({
            dataType: 'json',
    sequentialUploads: true,
    formData : {name:'thedate',value:getDate}
});

Then to add more params
           //name of param  // value
formData : [{name:'thedate',value:getDate},{name:'thedate2',value:'seconddate'},etc..]

Example:
[ { name: 'a', value: 1 }, { name: 'b', value: 2 } ]

Changing thedate with whatever you want to name the param
Though it sounds like a simple object should work fine
           //name:value
formData : {thedate:getDate}

