// 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);