javascript StringBuilder prototype implementation

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("");
}

Reproduced in: https: //www.cnblogs.com/hubcarl/archive/2010/07/03/1770374.html