js0018

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通过函数访问私有变量 而不是通过对象访问

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<!DOCTYPE html>
<html>
<head>
  <title>Private variables are accessed through functions and not through objects</title>
  <meta charset="utf-8">
  <script src="../assert.js"></script>
  <link rel="stylesheet" type="text/css" href="../assert.css">
</head>
<body>
	<script>
	  function Ninja() {
      var feints = 0;
      this.getFeints = function(){
        return feints;
      };
      this.feint = function(){
        feints++;
      };
    }
    var ninja1 = new Ninja();
    ninja1.feint();

    var imposter = {};
    imposter.getFeints = ninja1.getFeints;

    assert(imposter.getFeints () === 1,
          "The imposter has access to the feints variable!");
	</script>
</body>
</html>