dynamically resize a textarea

function resizeTextarea () {
    while (this.get("scrollHeight") > this.get("offsetHeight")) {
        this.set("rows", this.get("rows") + 1);
    }
    while (this.get("rows") > 3 && this.get("scrollHeight") < this.get("offsetHeight")) {
        this.set("rows", this.get("rows") - 1);
    }
}