Correct way to pass data to Jquery Ajax

Whats the correct way to pass data to ajax using jquery. I have the following method and I want to pass the CSRF token from a meta tag but it doesn't work.

<meta name="csrf-token" content="{{ csrf_token() }}">


$(document).on("change", ".fallback .inputfile", function() {
    $.ajax({
        url: "/upload",
        type: 'POST',
        cache: false,
        data:  {
            _token: $('meta[name="csrf-token"]').attr('content')
        },
        files: $(":file", this),
        iframe: true,
        processData: false
    }).complete(function(data) {
        console.log(data);
        // $('#img-thumb').attr('src', data.path);
        // $('input[name="job_logo"]').val(data.path);
    });
});

I've followed the documentation from the following source http://ift.tt/1V6m72A

I get tokenmismatch error. Note this is using Laravel 5.1

via Chebli Mohamed