如何将php标签放入.js文件？

I have code javascript with tag php in one file, in footer.html exactly. The php tag is work for calling method in a controller using url. when I separate the JS from footer.php in files .js the tag php is not working.

<?php echo site_url('index.php/master_ekspor/ajax_edit/')?>/

How to add/use/put php function on .JS file?

This is my .js function ?

function edit_ekspor(id)
        {
              save_method = 'update_ekspor';
              $('#form')[0].reset(); // reset form on modals

              //Ajax Load data from ajax
              $.ajax({
                url : "<?php echo site_url('index.php/master_ekspor/ajax_edit/')?>/" + id,
                type: "GET",
                dataType: "JSON",
                success: function(data)
                {

                    $('[name="id_ekspor"]').val(data.id_ekspor);
                    $('[name="nm_industri"]').val(data.nm_industri);
                    $('[name="e_berat"]').val(data.e_berat);
                    $('[name="e_nilai"]').val(data.e_nilai);
                    $('[name="tahun"]').val(data.tahun);


                    $('#modal_form').modal('show'); // show bootstrap modal when complete loaded
                    $('.modal-title').text('Edit Data Ekspor'); // Set title to Bootstrap modal title

                },
                error: function (jqXHR, textStatus, errorThrown)
                {
                    alertify.error("Gagal Mendapatkan Data");
                }

            });
        }

You can not write PHP code in the javascript file. You should declare url a variable in header section as:

<script>
var url = "<?php echo site_url('index.php/master_ekspor/ajax_edit/')?>";
</script>

Then use that variable in .js file as below.

function edit_ekspor(id)
        {
              save_method = 'update_ekspor';
              $('#form')[0].reset(); // reset form on modals

              //Ajax Load data from ajax
              $.ajax({
                url : url +"/" + id,
                type: "GET",
                dataType: "JSON",
                success: function(data)
                {

                    $('[name="id_ekspor"]').val(data.id_ekspor);
                    $('[name="nm_industri"]').val(data.nm_industri);
                    $('[name="e_berat"]').val(data.e_berat);
                    $('[name="e_nilai"]').val(data.e_nilai);
                    $('[name="tahun"]').val(data.tahun);


                    $('#modal_form').modal('show'); // show bootstrap modal when complete loaded
                    $('.modal-title').text('Edit Data Ekspor'); // Set title to Bootstrap modal title

                },
                error: function (jqXHR, textStatus, errorThrown)
                {
                    alertify.error("Gagal Mendapatkan Data");
                }

            });
        }