function stripBlankChar(html) {
  var chars = html.split("");
  chars = chars.filter(function (char) {
    var c = char.charCodeAt(0);
    if (c === 127) return false;
    if (c <= 31) {
      if (c === 10 || c === 13) return true;
      return false;
    }
    return true;
  });
  return chars.join("");
}
remove invisible characters

@param {String} html
@return {String}