title: argument problem On function argument ($0,$1);+jquery,js?
body: <p>Doubt On function($0,$1);
   // $0,$1  two argument
  <strong>My question is this two argument are Not defined But it hold some data on it ???</strong></p>
  
  <p>can any on help to Understand
  how this two argument run;</p>
  
  <pre><code>function strip_tags(input, allowed) {
      allowed = (((allowed || "") + "").toLowerCase().match(/&lt;[a-z][a-z0-9]*&gt;/g) || []).join(''); 
     //console.log('-----------&gt;'+allowed.join('ss'));
      var tags = /&lt;\/?([a-z][a-z0-9]*)\b[^&gt;]*&gt;/gi,
          commentsAndPhpTags = /&lt;!--[\s\S]*?--&gt;|&lt;\?(?:php)?[\s\S]*?\?&gt;/gi;
      return input.replace(commentsAndPhpTags,'').replace(tags, function ($0, $1) { // need help to understand $0 , $1
        //console.log('-----------&gt;'+$1);
          return allowed.indexOf('&lt;' + $1.toLowerCase() + '&gt;') &gt; -1 ? $0 : '';
      });
  }
  </code></pre>