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<html> <body> <script type="text/javascript"> function StringBuffer () { this._strings_ = new Array(); } StringBuffer.prototype.append = function(str) { this._strings_.push(str); }; StringBuffer.prototype.toString = function() { return this._strings_.join(""); }; var d1 = new Date(); var str = ""; for (var i=0; i < 10000; i++) { str += "text"; } var d2 = new Date(); document.write("Concatenation with plus: " + (d2.getTime() - d1.getTime()) + " milliseconds"); var buffer = new StringBuffer(); d1 = new Date(); for (var i=0; i < 10000; i++) { buffer.append("text"); } var result = buffer.toString(); d2 = new Date(); document.write("<br />Concatenation with StringBuffer: " + (d2.getTime() - d1.getTime()) + " milliseconds"); </script> </body> </html>