send data from php to javascript [duplicate]

Question

I have a question regarding data transmission from php to javascript. I gather some data from database and I format them like this:

for($i=0;$i<(sizeof($lt_periods_query['period_id']));$i++){

    $period_id   = $lt_periods_query['period_id'][$i];
    $lt_id       = $lt_periods_query['lt_id'][$i];
    $period_name = $lt_periods_query['period_name'][$i];
    $fDate       = $lt_periods_query['fromDate'][$i];
    $tDate       = $lt_periods_query['toDate'][$i];
    $minStay     = $lt_periods_query['min_stay'][$i];
    $nightly_rate= $lt_periods_query['nightly_rate'][$i];

    if (strStartsWith($fDate, $currentYear)=='true'){
        $year = $currentYear;
    } else if(strStartsWith($fDate, $nextYear)=='true'){
        $year = $nextYear;
    }

    $temp_period_details   =  array();
    $temp_period_details['period_id'] = $period_id;
    $temp_period_details['lt_id'] = $lt_id;
    $temp_period_details['period_name'] = $period_name;
    $temp_period_details['fromDate'] = $fDate;
    $temp_period_details['toDate'] = $tDate;
    $temp_period_details['min_stay'] = $minStay;
    $temp_period_details['nightly_rate'] = $nightly_rate;

    $periods[$year][$period_name] = $temp_period_details;
}

And I am able to see them when I print as like this:

echo "RULE for 6 days <br>";
$days= '5';
$selPeriod = 'off_peak';
$selYear = '2011';
echo $periods[$selYear][$selPeriod]['period_id'];
echo "<br>";
echo $periods[$selYear][$selPeriod]['lt_id'];
echo "<br>";
echo $periods[$selYear][$selPeriod]['period_name'];

I know that php is working on the server side and javascript is working on the client side. I want to get the data from javascript side by sending some parameters like this (I know why this is not working but I do not know how I can achieve such data transfers):

    <script type="text/javascript">

    $(function(){

        getData();

        function getData(){

            var days= '5';
            var selPeriod = 'off_peak';
            var selYear = '2011';


            //var xxx     = '<?php echo $periods[\''+selYear+'\'][\''+selPeriod+'\'][\'fromDate\'] ;?>';
            //var xxx = '<?php include($periods['2011']['off_peak'][''])?>;

        }

    });

Can anyone advice me a way to gather data from php to javascript by sending some parameters.

Answer 1

To communicate data structures from PHP to Javascript, inject a JSON value like this:

<?php
     $xdata = array(
          'foo'    => 'bar',
          'baz' => array('green','blue')
     );
?>
<script type="text/javascript">
    var xdata = <?php echo json_encode($xdata); ?>;

    alert(xdata['foo']);
    alert(xdata['baz'][0]);

    // Dot notation can be used if key/name is simple:
    alert(xdata.foo);
    alert(xdata.baz[0]);
</script>

This can be used to properly escape scalars, arrays, objects, etc.