How to pass the value of a PHP function to a Javascript variable?

Question

<script>
    function myFunc(a){
        document.getElementById("col2").innerHTML=a; 
        var str=a;
        if(str.charAt(0)=="c"){
            document.getElementById("col2").innerHTML="credit_card";
            var x=document.getElementById("col2").innerHTML;
            document.getElementById("col2").innerHTML= "<?php echo cc_print_info("<script> document.write(x) </script>") ;?>  ";
        }   
        
    }
</script>

I need to pass the value of cc_print_info() into document.getElementById("col2").innerHTML

I tried in the way mentioned in the code but it isn't working

Let me know how to do this

Please can you explain more.. What exactly you wanna do?? and what is `cc_print_info()` — Vinayak, Sep 30 '20 at 19:52
Do not mix client-side and server-side web scripting. If your PHP function cc_print_info is scripted as the PHP function, then you need to call it (and that functions returns the calculated result back). See https://stackoverflow.com/a/2379251/2103539 for more explanation. You would want to script the AJAX request to get the PHP function results AFTER the page was loaded in a web browser. — Matt Sergej Rinc, Sep 30 '20 at 20:41
@Vinayak cc_print_info() actually is a PHP function which does some MySQL queries and returns the value to the Javascript myFunc() — Sadikul Alim Toki, Oct 01 '20 at 05:15

score 0 · Answer 1 · answered Oct 01 '20 at 01:29

You should not use PHP inside JS script - it will not work but you can use PHP that generates JS script for example just variable assignment:

example code:

<!DOCTYPE html>

<html>

    <head>
    </head>

    <body>
        <?php

            function cc_print_info($a, $b) { return $a + $b; };

            echo '<script>' . PHP_EOL;
            echo "var phpReturn = " . cc_print_info(2, 3) . ';' . PHP_EOL;
            echo '</script>' . PHP_EOL;

        ?>

        <script>
            function myFunc(a, phpReturn){

                document.getElementById("col2").innerHTML=a; 
                var str=a;
                if(str.charAt(0)=="c"){
                    document.getElementById("col2").innerHTML="credit_card";
                    var x=document.getElementById("col2").innerHTML;
                    document.getElementById("col2").innerHTML= phpReturn;
                }   
                
            }
        </script>

    </body>

</html>

note that PHP must be before the script that uses returned value of cc_print_info.

Code above generates this HTML:

<!DOCTYPE html>

<html>

    <head>
    </head>

    <body>
        <script>
var phpReturn = 5;
</script>

        <script>
            function myFunc(a, phpReturn){

                document.getElementById("col2").innerHTML=a; 
                var str=a;
                if(str.charAt(0)=="c"){
                    document.getElementById("col2").innerHTML="credit_card";
                    var x=document.getElementById("col2").innerHTML;
                    document.getElementById("col2").innerHTML= phpReturn;
                }   
                
            }
        </script>

    </body>

</html>

so for a browser looks like no problem since you have

var phpReturn = 5;

you pass to your function:

function myFunc(a, phpReturn){

and use it:

document.getElementById("col2").innerHTML= phpReturn;

But the thing is I need to pass the value of 'a' in **myFunc()** into **cc_print_info()** as well. In that case, what should I do? @Jimmix — Sadikul Alim Toki, Oct 01 '20 at 05:11
@SadikulAlimToki for that you need to make HTTP request to the PHP page like for eg you do with [form](https://www.w3schools.com/php/php_forms.asp) or make from JS [XHR Request](https://javascript.info/xmlhttprequest). Then no matter the method you have chosen PHP returns value of the cc_print_info() as a normal web text that JS is able to read as a content. PHP can read your `a` from JS by reading that JS request data from GET or POST [see tutorial](https://www.tutorialspoint.com/php/php_get_post.htm) — Jimmix, Oct 01 '20 at 09:47
I know this isn't at all good to say but can you please build the code for me if you can as I am still unable to execute. I really need this at the moment. — Sadikul Alim Toki, Oct 01 '20 at 16:41
@SadikulAlimToki I afraid I would not do that but I would suggest creating a new question that shows what you did with the information I provided and additionally a description of the problems you had when you tried to get it working. — Jimmix, Oct 01 '20 at 17:56

How to pass the value of a PHP function to a Javascript variable?

1 Answers1