title: how to fix Nan javascript
body: <p>when I start to write in the htPrice field, Nan appears in the ttcPrice field, how can i fix this?</p>
  <pre><code>calculatTTC() {
       const htPrice = parseFloat(this.htpriceTargets[0].value);
       const tvaPercent = parseFloat(this.tvaTargets[0].value);
       const ttcPrice= parseFloat(preTaxPrice + vatPercent);
      if (isNaN(htPrice) &amp;&amp; isNaN(tvaPercent)) {
          this.ttcPriceTargets[0].value = 'the value is not correct';
      } else {
          this.ttcPriceTargets[0].value = ttcPrice;
      }
  
  }
  </code></pre>