title: how to concat string with dynamic value if that value exists
body: <p>Suppose I have a variable <code>data</code>:</p>
  
  <pre><code>var data = 6;
  </code></pre>
  
  <p>If we have <code>data</code> value and it's greater than 5 then the output should be:</p>
  
  <pre><code>"Hello x, 6 is your promo code"
  </code></pre>
  
  <p>If we don't have a <code>data</code> value, or the value is less than 5 then the output should be:</p>
  
  <pre><code>"Hello x"
  </code></pre>
  
  <p>How can I do this with a single line of JavaScript?</p>