function checkAllFields() {
	var chkAll = document.getElementById('checkAll');
	var checks = document.getElementsByName('bookcase_content[]');
	var boxLength = checks.length;
	var allChecked = false;
	
		if ( chkAll.checked == true )
		{
			for ( i=0; i < boxLength; i++ )
			checks[i].checked = true;
		}
		else
		{
			for ( i=0; i < boxLength; i++ )
			checks[i].checked = false;
		}
	
}