title: How to get Contact Form 7 field values in javascript?
body: <p>Please help me, i've the javascript allmost done. Only the last part is very difficult.
  I've used the calculator plugin for contact form7, to calculate the BMI, this works perfectly.
  To hide the BMIhigh text also works, and the click</p>
  
  <pre><code>Length (cm):
  &lt;label id="centi"&gt;[number* cm min:130 max: 220]&lt;/label&gt;
  
  Hight (kilo):
  &lt;label id="kilo"&gt;[number* kilo min:40 max:140]&lt;/label&gt;
  
  &lt;label id="calcbutton"&gt;[calculate_button "calculate"]&lt;/label&gt;
  
  &lt;label id="calc"&gt;[calculation calculate precision:1 "kilo / ((cm / 100) * (cm / 100))"]&lt;/label&gt; 
  &lt;label id="BMIhigh"&gt; 
  Your BMI is too high
  &lt;/label&gt;
  [submit "Send"]
  </code></pre>
  
  <p>At the bottom i've got the following code:</p>
  
  <pre><code>// Hide the BMIhigh text field by default
  document.getElementById("BMIhigh").style.display = 'none';
  // On every 'click' on the calculator call the displayTextField function
  document.getElementById("calcbutton").addEventListener("click", displayTextField);
    function displayTextField() {
      // Get the inserted values for centi and kilo and calculate the BMI again 
      // for the function without the help of the calculator build in into the extra plugin.
     var centimeter = +document.getElementById("centi").value;
     var kilogram = +document.getElementById("kilo").value;
     var BMIvar = kilogram / ( ( centimeter / 100 ) * ( centimeter / 100 ) );
      // If BMIvar higher than 30 it is too high, the text should show. 
      // THIS LAST PART DOES NOT WORK
      if(BMIvar &gt; 30) {
       document.getElementById("BMIhigh").style.display = 'block';
      } else {
        document.getElementById("BMIhigh").style.display = 'none';
      }
    }
  &lt;/script&gt; ```
  </code></pre>