JavaScript判断数组是否包含指定元素的实现方法

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
<body>
<script>
  Array.prototype.S = String.fromCharCode(2);
  Array.prototype.in_array = function (e) {
    var r = new RegExp(this.S + e + this.S);
    return (r.test(this.S + this.join(this.S) + this.S));
  };
  var arr = ["a", "bcc"];
  console.log(arr.in_array("c"))
</script>
</body>
</html>