increment php variable used in javascript

Question

I wanted to display a graph in javascript using data from php. My code is:

<?php $i = 20; ?>
while (data.length < totalPoints) {
    array_js.push(<?php echo json_encode($array_php[++$i][1]);?>);
}

The problem is that even though $i is declared before the while loop, it gets back to 20 all the time, so the data pushed in array_js is always $array_php[21][1].

Edit: here is more code, (not same variable name...)

startConn(); //connect to database

$query = "SELECT * FROM Reading";
$data = getAllDatas($query);
?>

<script type="text/javascript">
    $(function() {

    var data = [], totalPoints = 300;

        function getRandomData() {

            <?php $i = 20; ?>
            while (data.length < totalPoints) {
                data.push(<?php echo json_encode($data[--$i][1]);?>);
                //data.push(<?php echo ++$i;?>);
            }
        } // END getRandomData()

You can't mix php and javascript in this way. What is your goal? Why you want read a php array in javascript? — fusion3k
– fusion3k, Commented Feb 10, 2016 at 1:02
why not just encode your php array from the start, then make your way into pushing whatever values you have there — Kevin
– Kevin, Commented Feb 10, 2016 at 1:06
can show you more code? the javascript reside in html page, I suppose. Javascript can't use php data. you have to set the complete javascript array in php. but if you show more code, we can be more accurate — fusion3k
– fusion3k, Commented Feb 10, 2016 at 1:07
The problem is not the php array. I want to walk through the php array and to do that I need to increment $i and it seems that I am not able to achieve that because it does reset automatically. — Rossygnol
– Rossygnol, Commented Feb 10, 2016 at 1:10

Nadimul De Cj · Accepted Answer · 2016-02-10 04:53:18Z

1

You have a misunderstanding on how server side and client side code work.
I think this may help you

$(function() {
    var data = [], totalPoints = 3;
    var i = <?php $i = 1;echo $i; ?>;
    var j = parseInt(i);
    var arr = <?php echo json_encode($data); ?>;

    function getRandomData() {
        while (data.length < totalPoints) {
            data.push(arr[j][1]);
            j++;
        }
        return data;
    }
    var data1 = getRandomData();
    console.log(data1);
});

answered Feb 10, 2016 at 4:53

Nadimul De Cj

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1 Comment

Rossygnol Over a year ago

Thank you very much, it works perfect. I didn't know that it was possible to pass more complex variables like multidimensional arrays. My lack of knowledge in javascript doesn't help. should probably spend some time learning it.

Lee Balino · Accepted Answer · 2016-02-10 03:54:54Z

0

Try this one. You can pass the value of the php variable using echo while declaring another variable on the java script.

<?php $i = 20; ?>
var i = <?php echo $i;?>;
while (data.length < totalPoints) {
    array_js.push(<?php echo json_encode($array_php[++i][1]);?>);
}

answered Feb 10, 2016 at 3:54

Lee Balino

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1 Comment

Rossygnol Over a year ago

Haven't tried your code but I doubt it will work since 'i' cannot be seen in a php code. Might be wrong though...

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