PHP / Ajax / Jquery ? Keep polling external PHP script till it returns a value

Question

I have a main.php page which I want to show a message like : "Checking for completion.."

Main.php will keep calling (without leaving the page) "function.php",

function.php returns with a boolean .

If function.php returns true: I want main.php to write that the operation completed if it returns false, it will need to keep checking untill it returns true.

I am unfamiliar with Ajax/JQuery but from what I understood it might be the best approach. Is someone able to provide me a (working) example of how to accomplish this ?

Thanks!

Ajax is what you want. Ajax stands for asynchronous javascript and xml. Jquery provides a wrapper for pure ajax, but you can run ajax via pure javascript. Take a look at this example. w3schools.com/php/php_ajax_database.asp — Raphael Rafatpanah
– Raphael Rafatpanah, Commented Jul 15, 2015 at 15:37

Vanojx1 · Accepted Answer · 2015-07-15 15:36:08Z

1

Try this

function check(){
return $.ajax({
    url: 'function.php',
    type:'POST',
    success: function(risp){
        if(!risp){
            check();
        }else{
            alert("finished!!");
        }
    },
    failure: function(jqXHR, textStatus, errorThrown){
        console.log(textStatus);
    }
});
}

check();

answered Jul 15, 2015 at 15:36

Vanojx1

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2 Comments

datether Over a year ago

I noticed that when it enters else { alert("finished !"); } the value of risp is lost (set to false). So if my script would '1' I can't further process that. How would I go about doing something like : i.e. if (risp == '1'){ alert(risp); } }else{ check() }

Vanojx1 Over a year ago

in your php use echo "finished"; and then use if(risp == "finished"){ .... }else{ check(); } .... or you wanna return a different value from finished??

Think Different · Accepted Answer · 2015-07-15 15:36:16Z

1

main.php

<script type="text/javasctipt">
   var interval = window.setInterval(function(){
       $.ajax({
          type: 'POST',
          data: {key1: value1, key2: value2},
          url: 'function.php',
          success: function(response){
              if(response == 'true'){
                   console.log('Operation Completed'); //<== Completed message use it as you want 
                   window.clearInterval(interval);
               }
          }
       });
    },2000);
</script>

Following script will give you a good idea about what you require. I will call function.php every 2 seconds.:

function.php

<?php

   //Do you processing
   $result = 'true';

   echo $result;

 ?>

answered Jul 15, 2015 at 15:36

Think Different

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1 Comment

datether Over a year ago

This seems to come closest to what I need, after trying to run it (corrected the typo to javascript) it just keeps requesting function.php :

var interval = window.setInterval(function(){        $.ajax({           type: 'POST',           url: 'function.php',           success: function(response){               if(response == 'true'){                    window.clearInterval(interval);                }           }        });     },2000);

Any idea what might be causing this ?

Erwin Moller · Accepted Answer · 2015-07-15 15:42:05Z

1

In summary: You main.php delivers HTML to a webbrowser. In your HTML you write some JavaScript (using XHR/'AJAX') that will start polling the server to check if a certain process is completed.

The script on the server (functions.php) returns true or false to the client. In case of false, you want to check again in, say 5 seconds. Right?

If this is all new to you, you have a lot to dive into, but here are a few pointers:

Good introduction to XMLHttpRequest

How to use window.setTimeout

If you only want a true or false returnvalue, you don't have to use XML. Just let the server return "true" or "false" as a string.

And last: Make sure your functions.php doesn't need to perform heavy operations to find out if the "process" is finished. If you do, you will put a lot of load on the server during the polling if you have many clients using the page.

answered Jul 15, 2015 at 15:42

Erwin Moller

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1 Comment

datether Over a year ago

Thank you for your contribution

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