codeigniter 3中jquery ajax发布的URL

I have some problem, 'query in views undefined'. How can I solve it ?

Javascript

function search() {
  var query_value = $('input#name').val();
  if (query_value !== '') {
    $.ajax({
      type: "POST",
      url: <?php echo base_url()?>
      "index",
      data: {
        query: query_value
      },
      cache: false,
      success: function(html) {
        $("table#resultTable tbody").html(html);
      }
    });
  }
  return false;
}

javascript in views

$search_string = preg_replace("/[^A-Za-z0-9]/", " ", $_POST['query']);

link in html

<script type="text/javascript" src="<?php echo base_url()?>assets/scripts/triggers.js"></script>