i can't understand the working flow of the following code, can anyone explain me?

i can't understand the working flow of the following code, can anyone explain me?

<!DOCTYPE html>
<html>
<head>
<script>
$(document).ready(function(){
  $("#myInput").on("keyup", function() {
    var value = $(this).val().toLowerCase();
    $("#myTable tr").filter(function() {
      $(this).toggle($(this).text().toLowerCase().indexOf(value) > -1)
    });
  });
});
</script>
<style>
table {
    font-family: arial, sans-serif;
    border-collapse: collapse;
    width: 100%;
}

td, th {
    border: 1px solid #dddddd;
    text-align: left;
    padding: 8px;
}

tr:nth-child(even) {
    background-color: #dddddd;
}
</style>
</head>
<body>

<h2>Filterable Table</h2>
<p>Type something in the input field to search the table for first names, last names or emails:</p>  
<input id="myInput" type="text" placeholder="Search..">
<br><br>

<table>
  <thead>
    <tr>
      <th>Firstname</th>
      <th>Lastname</th>
      <th>Email</th>
    </tr>
  </thead>
  <tbody id="myTable">
    <tr>
      <td>John</td>
      <td>Doe</td>
      <td> john@example.com</td>
    </tr>
    <tr>
      <td>Mary</td>
      <td>Moe</td>
      <td> mary@mail.com</td>
    </tr>
    <tr>
      <td>July</td>
      <td>Dooley</td>
      <td> july@greatstuff.com</td>
    </tr>
    <tr>
      <td>Anja</td>
      <td>Ravendale</td>
      <td> a_r@test.com</td>
    </tr>
  </tbody>
</table>
  
<p>Note that we start the search in tbody, to prevent filtering the table headers.</p>

</body>
</html>





in above code i can't understand, because the filter() function is filled by a argument which is not like as spacified in the documentation of filter() so can anyone explain me this ?