title: javascript validation for allow -1 and all positive numbers in text box
body: <p>I am trying to validate a text box to allow all positive numbers including -1 in it.</p>
  
  <p>i tried this, which will work for allowing only positive numbers
  <code></p>
  
  <pre><code>  function allownumbers(e, txtBox) {
          var key;
  
          key = (e.keyCode) ? e.keyCode : e.charCode;
          if (e.charCode == 0) {
              return true;
          }
          if ((key &lt; 48 || key &gt; 57) &amp;&amp; (key != 46) &amp;&amp; (key != 44)) {               
              return false;                
          }
          if (key == 46) {
              if ((txtBox.value).indexOf('.') != -1) {
                  return false;
              }
          }
          if (key == 44) {
              if ((txtBox.value).indexOf(',') != -1) {
                  return false;
              }
          }
          return true;
      }
  </code></pre>
  
  <p></code></p>
  
  <p>But how to allow  -1(only) with all positive numbers
  Thanks in advance</p>