textarea 자동높이가 잘안되어서그런데요~~ 고수님들~~ 굽신굽신~~

<script type="text/javascript">
/*textarea 자동 높이 조절 */
$(document).ready(function() {
// 모두 로딩되었을때
$(".textArea").autoGrow();
//autoRows(document.finquiryform.in_content);
});
</script>



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js 소스인데요

//Private variables
var colsDefault = 0;
var rowsDefault = 0;
//var rowsCounter = 0;

//Private functions
function setDefaultValues(txtArea)
{
colsDefault = txtArea.cols;
rowsDefault = txtArea.rows;
//rowsCounter = document.getElementById("rowsCounter");
}

function bindEvents(txtArea)
{
txtArea.onkeyup = function() {
grow(txtArea);
}
}

//Helper functions
function grow(txtArea)
{
    var linesCount = 0;
    var lines = txtArea.value.split('\n');

    for (var i=lines.length-1; i>=0; --i)
    {
        linesCount += Math.floor((lines[i].length / colsDefault) + 1);
    }

    if (linesCount >= rowsDefault)
        txtArea.rows = linesCount + 1;
else
        txtArea.rows = rowsDefault;
//rowsCounter.innerHTML = linesCount + " | " + txtArea.rows;
}

//Public Method
jQuery.fn.autoGrow = function(){
return this.each(function(){
setDefaultValues(this);
bindEvents(this);
});
};


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왜안될까요??