jQuery .map returns one empty value "" in multiple image upload

I am trying to save all IDs from selected images as a string. It works almost perfect, but it is one problem. Every time a user select a photo, the code makes one empty value. In the console if I watch the IDs it returns this: [“”, “66”, “125”, “97”, “58”, “59”]

Why does it return one “” ? any ideas?

` imageUploader.on( ‘close’, function() {
//var attachment = imageUploader.state().get(‘selection’).first().toJSON();
var attachment = imageUploader.state().get(‘selection’).toJSON();
var ids = attachment.map( function (attachment) {
return attachment.id;
console.log(ids);
});
jQuery.each(attachment, function(){
jQuery(‘#image-tag’).prepend(‘<img src=”‘+attachment.id+'” />’)
});
hidden.setAttribute( ‘value’, ids.join(‘,’) );
});`