title: Why is my JavaScript function "a" not defined?
body: <p>When I call my JavaScript function B, the JavaScript console in Firefox said that function A is not defined, but on Chrome browser it's defined. And when I call function "A" in body segment:</p>
  
  <pre><code>&lt;input type="button" onclick="A()" value=" ..A.. "&gt;
  </code></pre>
  
  <p>Firefox said that function B is not defined. Why? </p>
  
  <pre><code>&lt;html&gt;
      &lt;head&gt;
          &lt;script language="javascript" type="text/javascript"&gt;
              function B() {
                  alert(" hi B ");
                  document.write('&lt;br&gt;&lt;br&gt;&lt;input type="button" onClick="A()" value=" ..A.."&gt;');
              };
  
              function A() {
                  alert(" hi A");
                  document.write('&lt;br&gt;&lt;br&gt;&lt;input type="button" onclick="B()" value=" ..b.."&gt;');
                  if (window.WebCL == undefined) {
                      alert("Unfortunately your system does not support WebCL. ");
                      return false;
                  }
              }
          &lt;/script&gt;
      &lt;/head&gt;
      &lt;body&gt;
          &lt;input type="button" onclick="B()" value=" ..B.. "&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>