var data = new FormData();
jQuery.each(jQuery('#file')[0].files, function(i, file) {
data.append('file-'+i, file);
});
jQuery.ajax({
url: 'php/upload.php',
data: data,
cache: false,
contentType: false,
processData: false,
type: 'POST',
success: function(data){
alert(data);
}
});