console.time('111');var str = "";for (var i=0; i < 10000; i++) {    str += "text";}console.timeEnd('111');console.time('2222');function StringBuffer () {  this._strings_ = new Array();}StringBuffer.prototype.append = function(str) {  this._strings_.push(str);};StringBuffer.prototype.toString = function() {  return this._strings_.join("");};var buffer = new StringBuffer();for (var i=0; i < 10000; i++) {    buffer.append("text");}var result = buffer.toString();console.timeEnd('2222');