function strip_tags(input, allowed) {
    //  discuss at: http://phpjs.org/functions/strip_tags/
    // original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // improved by: Luke Godfrey
    // improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    //    input by: Pul
    //    input by: Alex
    //    input by: Marc Palau
    //    input by: Brett Zamir (http://brett-zamir.me)
    //    input by: Bobby Drake
    //    input by: Evertjan Garretsen
    // bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // bugfixed by: Onno Marsman
    // bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // bugfixed by: Eric Nagel
    // bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // bugfixed by: Tomasz Wesolowski
    //  revised by: Rafał Kukawski (http://blog.kukawski.pl/)
    //   example 1: strip_tags('<p>Kevin</p>
<b>van</b> <i>Zonneveld</i>', '<i><b>');
    //   returns 1: 'Kevin <b>van</b> <i>Zonneveld</i>'
    //   example 2: strip_tags('<p>Kevin <img src="someimage.png" onmouseover="someFunction()">van <i>Zonneveld</i></p>', '<p>');
    //   returns 2: '<p>Kevin van Zonneveld</p>'
    //   example 3: strip_tags("<a href='http://kevin.vanzonneveld.net'>Kevin van Zonneveld</a>", "<a>");
    //   returns 3: "<a href='http://kevin.vanzonneveld.net'>Kevin van Zonneveld</a>"
    //   example 4: strip_tags('1 < 5 5 > 1');
    //   returns 4: '1 < 5 5 > 1'
    //   example 5: strip_tags('1 <br/> 1');
    //   returns 5: '1  1'
    //   example 6: strip_tags('1 <br/> 1', '<br>');
    //   returns 6: '1 <br/> 1'
    //   example 7: strip_tags('1 <br/> 1', '<br><br/>');
    //   returns 7: '1 <br/> 1'

    allowed = (((allowed || '') + '')
      .toLowerCase()
      .match(/<[a-z][a-z0-9]*>/g) || [])
      .join(''); // making sure the allowed arg is a string containing only tags in lowercase (<a><b><c>)
    var tags = /<\/?([a-z][a-z0-9]*)\b[^>]*>/gi,
      commentsAndPhpTags = /<!--[\s\S]*?-->|<\?(?:php)?[\s\S]*?\?>/gi;
    return input.replace(commentsAndPhpTags, '')
      .replace(tags, function($0, $1) {
        return allowed.indexOf('<' + $1.toLowerCase() + '>') > -1 ? $0 : '';
      });
}

function  strip_tags(str, allowed_tags) {
              var key = '', allowed = false;
              var matches = [];
              var allowed_array = [];
              var allowed_tag = '';
              var i = 0;
              var k = '';
              var html = '';
     
              var replacer = function(search, replace, str) {
                  return str.split(search).join(replace);
              };
     
              // Build allowes tags associative array
              if (allowed_tags) {
                  allowed_array = allowed_tags.match(/([a-zA-Z]+)/gi);
              }
     
              str += '';
     
              // Match tags
              matches = str.match(/(<\/?[\S][^>]*>)/gi);
     
              // Go through all HTML tags
              for (key in matches) {
                  if (isNaN(key)) {
                      // IE7 Hack
                      continue;
                  }
     
                  // Save HTML tag
                  html = matches[key].toString();
     
                  // Is tag not in allowed list? Remove from str!
                  allowed = false;
     
                  // Go through all allowed tags
                  for (k in allowed_array) {
                      // Init
                      allowed_tag = allowed_array[k];
                      i = -1;
     
                      if (i != 0) { i = html.toLowerCase().indexOf('<'+allowed_tag+'>');}
                      if (i != 0) { i = html.toLowerCase().indexOf('<'+allowed_tag+' ');}
                      if (i != 0) { i = html.toLowerCase().indexOf('</'+allowed_tag)   ;}
     
                      // Determine
                      if (i == 0) {
                          allowed = true;
                          break;
                      }
                  }
     
                  if (!allowed) {
                      str = replacer(html, "", str); // Custom replace. No regexing
                  }
              }
     
              return str;
          }