javascript variable into php that is already into javascript

Question

i have tried this code:

<script type="text/javascript">
    var s = 0;
    document.getElementById('text').value = "<?php echo phpVal[s];?>";
</script>

the problem is how can i put the (s) value into (PHP) code.

Here's more context:

<head>
<?php $s = ["a","b","c"]; ?>
<script type="text/javascript">
function doFun(ss){
    var data = "<?php echo json_encode($s); ?>";
    document.getElementById('t').value = s[ss];
}
</script>
</head>
<body>
<input type="text" id="t" name="t" />
<button type="button" id="b" name="b" onclick="doFun(0)">doFun</button>
</body>

Are you trying to achieve the impossible? It is like mixing oil with water. — invisal
– invisal, Commented Oct 11, 2015 at 9:29
because you cannot mix the server-side script with client-side script. Of course, there are workaround but none of them truly mixing the code together. — invisal
– invisal, Commented Oct 11, 2015 at 9:49
@invisal with json encoding you can do the impossible ... try it if you want ;) — Anas
– Anas, Commented Oct 12, 2015 at 12:55

T.J. Crowder · Accepted Answer · 2015-10-11 09:32:25Z

2

You can't, by the time s has a value (on the client), the PHP code (on the server) has long-since completed.

What you do instead depends a lot on what your end goal is. You have a lot of options. Here are two of them:

Output the entire phpVal array/object to the client, and then index into it with s.

var s = 0;
var data = <?php echo json_encode(phpVal)%>;
document.getElementById('text').value = data[s];

Send s to the server via ajax, have the PHP code that runs in response to that request pick out the correct value from phpVal, and return that as the result of the ajax, putting it in the client-side input's value. For example:

JavaScript:

var s = 0;
var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
    if (xhr.readyState == 4 && xhr.status == 200) {
        document.getElementById('text').value = xhr.responseText;
    }
};
xhr.open("get-value.php?s=" + encodeURIComponent(s));
// You don't really need this ^
// for `0`, but many times when sending variables to the
// server, you do
xhr.send();

PHP for get-value.php (roughly):

<?php
header('Content-Type: text/plain');
$phpVal = /*...get the value however it is you do that...*/
echo $phpVal[$_GET['s']];
?>

But again it depends on what you're actually trying to do.

edited Oct 11, 2015 at 9:32

answered Oct 11, 2015 at 9:30

T.J. Crowder

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5 Comments

Anas Over a year ago

this solution maybe help but i don't need to connect with server and bring data ... i already have an array and i want to put it's value into (s) depend on the index that i want to send ... e.g.

Anas Over a year ago

<head> <?php $s = ["a","b","c"]; ?> <script type="text/javascript"> function doFun(ss){ var data = "<?php echo json_encode($s); ?>"; document.getElementById('t').value = s[ss]; } </script> </head> <body> <input type="text" id="t" name="t" /> <button type="button" id="b" name="b" onclick="doFun(0)">doFun</button> </body>

T.J. Crowder Over a year ago

@Anas: To improve/clarify your question, use the "edit" link on the question. As you can see, code in comments is not really readable. Edit: I've done it for you this time.

T.J. Crowder Over a year ago

@Anas: "i already have an array" You have an array on the server. If you want it on the client, you need to send it to the client (for instance, #1 above).

Anas Over a year ago

i used the first answer with json encoding ... actually i used json with mobile application but i tried here many ways to achieve my goad but nothing work except json ... anyway thank you sir for your answer and please if you can edit it because it should be 'var data = <?php echo json_encode($phpVal)?>;' not 'var data = <?php echo json_encode(phpVal)%>;' ^_^

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