AutoTextArea

/* setup */
var FormUtil = FormUtil || {} ;
FormUtil.TextArea = FormUtil.TextArea || {} ;

/* config */
FormUtil.TextArea.conf = {
    resizeClass: "auto-resize",
    resizeMin: 1,
    resizeMax: 30
};

/* resize func */
FormUtil.TextArea.autoResize = function(e){
    var conf = FormUtil.TextArea.conf;
    var textarea = e.target || e.srcElement || e;
    var rowCount = textarea.value.split("\n").length;
    rowCount = Math.min(conf.resizeMax, Math.max(conf.resizeMin, rowCount));
    textarea.setAttribute("rows", rowCount);
};

/* init event */
FormUtil.TextArea.init = function(e){
    var textarea = document.getElementsByTagName("textarea");
    var className = FormUtil.TextArea.conf.resizeClass;
    var regex = new RegExp("(^|\\s+)" + className + "($|\\s+)");
    for(var i=0,max=textarea.length;i<max;i++){
        var tmp = textarea.item(i);
        if(!(tmp.getAttribute("class") || tmp.getAttribute("className") || "").match(regex)) continue;
        if(window.addEventListener){
            tmp.addEventListener("keyup", FormUtil.TextArea.autoResize, false);
        } else if (window.attachEvent) {
            tmp.attachEvent("onkeyup", FormUtil.TextArea.autoResize);
        }
        FormUtil.TextArea.autoResize(tmp);
    }
}

/* onload event */
if(window.addEventListener) {
    window.addEventListener("load", FormUtil.TextArea.init, false);
} else if (window.attachEvent) {
    window.attachEvent("onload", FormUtil.TextArea.init);
}