Search notes:

JavaScript: operator instanceof

<!DOCTYPE html>
<html>
<head>
  <meta content="text/html;charset=utf-8" http-equiv="Content-Type">
  <title>instanceof</title>

  <script type="text/javascript">

    var out;
    function write_out(bool) {

      if (bool) {
        out.innerHTML += "Yes<br>";
      }
      else {
        out.innerHTML += "No<br>";
      }
    }

    
    function main() {

      table_ = document.createElement('table');
      tbody_ = document.createElement('tbody');
      table_.style.borderCollapse='collapse';

      table_.appendChild(tbody_);

      document.getElementsByTagName('body')[0].appendChild(table_);
    
      out = document.getElementById('out');

      write_out(new String('foo') instanceof  String);  // Yes
      write_out("bar" instanceof String);               //  No

  //  ---------------------------------------

      StringBaz = function() {};
      StringBaz.prototype = String.prototype;

      write_out(StringBaz instanceof String);           //  No

  //  ---------------------------------------

      var baz = new StringBaz();
      write_out(baz instanceof String);                 // Yes

    }

  </script>

</head>
<body onload='main()';>
  <div id="out"></div>
</body>
</html>

Github repository about-javascript, path: /operators/instanceof.html

JavaScript: operator instanceof

See also