title: How to prevent duplicate append data to a table in jquery/javascript?
body: <p>How can I avoid having the same data in my table?</p>
  
  <p>Here's the code:</p>
  
  <pre><code>var a = 0;
      $(document).on("change", "#txtInput",function(){
        var inputLength = this.value.length;
        if (inputLength &lt;= 9) { return; }
  
        $("#contenido").append("&lt;tr&gt;&lt;td&gt;" + this.value + "&lt;/td&gt;&lt;/tr&gt;");
        $("p").html('Total Bianuales: ' + (++a));
      });
  </code></pre>