Php - Pass Dynamic Value Via Parameter?

I am using this plugin [URL] I am using this code:

var uploader = new qq.FileUploader({
// pass the dom node (ex. $(selector)[0] for jQuery users)
element: document.getElementById('file-uploader'),
// path to server-side upload script
action: '/server/upload',
params: {item1:$('#txtName').val() }
});

Now when the request is made to server always the blank value goes to server instead of what the actual value is (I changed the value of textbox after the page has been loaded). I think the first default value of textbox is passed in this case. My question how can I pass the dynamic value of textbox to server?