Question

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how to access PHP variables from within JavaScript?

I am trying to pass a variable from mySQL to PHP then to JavaScript to perform some math on it then have the result displayed on page in a specific area (in a <p> element with a specific ID assigned to it). Is this possible or is there an easier solution?

Thanks!

I already know how to get the variable from MySQL to PHP just having trouble on what to do after that.

Here is my updated code after reading responses. Still not working but I am sure I’m doing something wrong!

<p id="p_id"><?php echo $price; ?></p>
<input type="radio" group="radio_group" value="Reduce 10%" onclick="radio_click();" />

<script type="text/javascript">
var price = <?php echo $price; ?>;

function radio_click() {
var target = document.GetElementById('p_id');
var final_number; // this will be variable your store the final number in

final_number = price * .9;
target.innerHTML = final_number;

}
</script>

Answer 1

In short, you have to pass the variable to the <script> tag as a string in a JavaScript friendly format (quotes and stuff).

<?php

$variable = 5;
$javaScriptAccessible = '
    <script type="text/javascript">
        var javaScriptAccessible = "'. $variable . '";
    </script>
';

echo $javaScriptAccesible;

Also, you could JSON it:

<?php

$variable = 5;
$javaScriptAccessible = '
    <script type="text/javascript">
        var javaScriptAccessible = '. json_encode($variable) .';
    </script>
';

echo $javaScriptAccessible;

With JSON, the quotes would be appended automatically.

Here you can see both in action: http://codepad.viper-7.com/Jyfw31

Update:

Here are more refined and, I think, better to understand examples: http://codepad.viper-7.com/1cloyB
Only thing you have to do, is use it on your radio buttons / elements.

I’d strongly suggest going with JSON, because it actually stands for JavaScript Object Notation, it has libraries in, probably, every single programming language on planet, and is specifically designed to pass JS data from one environment to other.

http://php.net/manual/en/function.json-encode.php here you can see multiple options you’re able to pass in order to render it differently.