代码中的0x20和0xA0是什么意思

  this.encodeHtml = function(s){
      return (typeof s != "string") ? s :
          s.replace(this.REGX_HTML_ENCODE,
                    function($0){
                        var c = $0.charCodeAt(0), r = ["&#"];
                        c = (c == 0x20) ? 0xA0 : c;
                        r.push(c); r.push(";");
                        return r.join("");
                    });
  };