js 光标处插入字符（ie，火狐兼容）

/**
 * 在光标的位置插入图片
 * @param {Object} myField
 * @param {Object} myValue
 */
function AddOnPos(myField, myValue)
{
	//IE support
	if (document.selection)
	{
	myField.focus();
	sel = document.selection.createRange();
	myValue = "[face]"+myValue+"[/face]";
	sel.text = myValue;
	sel.select();
	}
	//MOZILLA/NETSCAPE support
	else if (myField.selectionStart || myField.selectionStart == '0')
	{
	var startPos = myField.selectionStart;
	var endPos = myField.selectionEnd;
	// save scrollTop before insert
	var restoreTop = myField.scrollTop;
	myValue = "[face]"+myValue+"[/face]";
	myField.value = myField.value.substring(0, startPos) + myValue + myField.value.substring(endPos,myField.value.length);
	if (restoreTop > 0)
	{
	// restore previous scrollTop
	myField.scrollTop = restoreTop;
	}
	myField.focus();
	myField.selectionStart = startPos + myValue.length;
	myField.selectionEnd = startPos + myValue.length;
	} else {
	myField.value += myValue;
	myField.focus();
	}
}