title: integer empty variable javascript
body: <p>I don't know why this return undefined?</p>
  
  <pre><code>var array = [6, 4, 6, 9];
  var min;
  var findminimum =   function(){
          array.reduce(function(prev, cur, index, array) {
                      if (cur &lt; min) {
                          min = cur;
                      }
          }, 0);
          return min;
      };
  console.log(findminimum());
  </code></pre>
  
  <p>but when i set:</p>
  
  <pre><code>var min = 20;
  </code></pre>
  
  <p>it is run ok, so anyone can explain me how to properly define num variable?</p>