textarea自动加高代码

(function($){
$.fn.extend({
textareaAutoHeight: function (options) {
this._options = {
minHeight: 0,
maxHeight: 1000
}

this.init = function () {
for (var p in options) {
this._options[p] = options[p];
}
if (this._options.minHeight == 0) {
this._options.minHeight=parseFloat($(this).height());
}
for (var p in this._options) {
if ($(this).attr(p) == null) {
$(this).attr(p, this._options[p]);
}
}
$(this).keyup(this.resetHeight).change(this.resetHeight)
.focus(this.resetHeight);
}
this.resetHeight = function () {
var _minHeight = parseFloat($(this).attr("minHeight"));
var _maxHeight = parseFloat($(this).attr("maxHeight"));

if ($.support.leadingWhitespace) {
$(this).height(0);
}
var h = parseFloat(this.scrollHeight);
h = h < _minHeight ? _minHeight :
h > _maxHeight ? _maxHeight : h;
$(this).height(h).scrollTop(h);
if (h >= _maxHeight) {
$(this).css("overflow-y", "scroll");
}
else {
$(this).css("overflow-y", "hidden");
}
}
this.init();
}
});
})(jQuery)