textarea 현재 위치에 문자열 삽입

<script>
function insertAtCaret(areaId,text) {
	var txtarea = document.getElementById(areaId);
	var scrollPos = txtarea.scrollTop;
	var strPos = 0;
	var br = ((txtarea.selectionStart || txtarea.selectionStart == '0') ? 
		"ff" : (document.selection ? "ie" : false ) );
	if (br == "ie") { 
		txtarea.focus();
		var range = document.selection.createRange();
		range.moveStart ('character', -txtarea.value.length);
		strPos = range.text.length;
	}
	else if (br == "ff") strPos = txtarea.selectionStart;

	var front = (txtarea.value).substring(0,strPos);  
	var back = (txtarea.value).substring(strPos,txtarea.value.length); 
	txtarea.value=front+text+back;
	strPos = strPos + text.length;
	if (br == "ie") { 
		txtarea.focus();
		var range = document.selection.createRange();
		range.moveStart ('character', -txtarea.value.length);
		range.moveStart ('character', strPos);
		range.moveEnd ('character', 0);
		range.select();
	}
	else if (br == "ff") {
		txtarea.selectionStart = strPos;
		txtarea.selectionEnd = strPos;
		txtarea.focus();
	}
	txtarea.scrollTop = scrollPos;
}

$(document).ready(function() {
	$("#a").click(function() {
		var a = $("#myTextBoxSelector").getCursorPosition();
		alert(a);
	});
});
</script>

<textarea id="textareaid"></textarea>
<a href="#" onclick="insertAtCaret('textareaid','text to insert');return false;">Click Here to Insert</a>