// Initializes a new instance of the StringBuilder class // and appends the given value if supplied function StringBuilder(value) { this.strings = new Array(""); this.append(value); } // Appends the given value to the end of this instance. StringBuilder.prototype.append = function (value) { if (value) { this.strings.push(value); } } // Clears the string buffer StringBuilder.prototype.clear = function () { this.strings.length = 1; } // Converts this instance to a String. StringBuilder.prototype.toString = function () { return this.strings.join(""); }

// create a StringBuilder var sb = new StringBuilder(); // append some text sb.append("Some of those preparing for international "); sb.append("exams such as the TOEFL "); sb.append("need extra practice for the listening section"); // get the full string value var s = sb.toString(); alert(s);