title: Can't get value from input field after split to parts for calculate itself
body: <p>I want to sum some values when the user send values from a text field with addition symbol.</p>
  
  <p>After split the values of this field I get always NAN.</p>
  
  <p>I've tried several options (parseInt, parseFloat) as you see in the javascript Code, but can't get it work.</p>
  
  <p>Maybe there is someone who can help:</p>
  
  <p>My html Code:</p>
  
  <pre><code>&lt;input type="text" id="testsum" placeholder="gelieferte CBM" value="5+6+8+2" onblur="CbmErrechnen(this.value)"&gt;
  </code></pre>
  
  <p>My javascript:</p>
  
  <pre><code>function CbmErrechnen () {
              var parts = document.getElementById('testsum').value.split('+', 5);
              var zahl0  = parseInt((parts[0]).innerHTML, 10);
              var zahl1  = parseInt((parts[1]).innerHTML, 10);
              var zahl2  = parseFloat(parts[2]);
              var zahl3  = parseFloat(parts[3]);
              var zahl4  = parseFloat(parts[4]);
          var sum = (zahl0)+(zahl1);
              alert(sum);
              return false;
  
          }
  </code></pre>
  
  <p>Maybe there is someone who can help.</p>