send json post ajax javascript

1$.ajax({
2    url: 'users.php',
3    dataType: 'json',
4    type: 'post',
5    contentType: 'application/json',
6    data: JSON.stringify( { "first-name": $('#first-name').val(), "last-name": $('#last-name').val() } ),
7    processData: false,
8    success: function( data, textStatus, jQxhr ){
9        $('#response pre').html( JSON.stringify( data ) );
10    },
11    error: function( jqXhr, textStatus, errorThrown ){
12        console.log( errorThrown );
13    }
14});