Additional Code (more boxes)

<p>
Your [INSERT SOMETHING]: <input type="text" id="inputTxt2"><button id="submit2">submit</button> <a href="http://silencethroughwords.tumblr.com/readerinsert">What is this?</a>

<script type="text/javascript">
document.getElementById("submit2").addEventListener('click', function(){
   var s = escapeRegExp('Y/L/N'); // PUT WHATEVER EXPRESSION HERE BETWEEN THE SINGLE QUOTES
    var val = new RegExp(s, "ig");
  walk(document.body, val, document.getElementById("inputTxt2").value);
});

function escapeRegExp(str) {
  return str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&amp;");
}
</script>
</p>