title: RefenceError: UET is not defined
body: <p>I'm struggling to understand why this javascript error keeps popping up on my website and I can't reproduce it.
  I've followed the bing documentation to install their tracking pixel so I have this in my header :</p>
  
  <pre><code>  &lt;script&gt;
      (function(w,d,t,r,u){var f,n,i;w[u]=w[u]||[],f=function(){
        var o={ti:"xxxxxxxx"};o.q=w[u],w[u]=new UET(o),
                w[u].push("pageLoad")},n=d.createElement(t),n.src=r, n.async=1,
              n.onload=n.onreadystatechange=function(){var s=this.readyState;
                s&amp;&amp;s!=="loaded"&amp;&amp;s!=="complete"||(f(),n.onload=n.onreadystatechange=null)},
              i=d.getElementsByTagName(t)[0],i.parentNode.insertBefore(n,i)})
      (window,document,"script","//bat.bing.com/bat.js","uetq");
    &lt;/script&gt;
  </code></pre>
  
  <p>However in some browsers, the UET variable in this code, which is loaded by the url given as the <code>r</code> variable, seems to not be defined while it's only called when the url is loaded... </p>
  
  <p>If anybody can make sense of it before I reach out to bing, I'll be very thankful!</p>