重新加载函数而不重新加载页面

Question

I want to callout a function without the page is reloading. I know that this is possible with AJAX but i don't know how it works with calling a function.

I want to put a timer so it will reload the function every 3 seconds, so the users doesnt need to reload the page everytime to see if there is a new message.

$object = new Messages();
$object->ShowMessage($nick);

ShowMessage(); is the function that i want to call out every 3 seconds.

Full code :

public function ShowMessage() {

    $st = $this->db->prepare("SELECT * FROM bericht");
    $st->execute();
    if($st->rowCount() == 0){
        echo 'There is no message jet!';
    }  

        foreach ($st as $bericht){
        $uid = $bericht['uid'];

        $nick = $this->db->prepare("SELECT * FROM users WHERE id=?");
        $nick->bindParam(1, $uid);
        $nick->execute();

            foreach($nick as $name) {   

            $image = $name['foto'];

        if($image == 'nophoto.jpg'){
        echo '<img src="image/nophoto.jpg" width="60px" height="30px">';

        } else {
        echo '<img src="image/'; echo $image.'"'; echo ' width="60px" height="30px">';
        }
        echo json_encode($name['name']) .': ';
        echo json_encode($bericht['message']).' <br> ';

    }

    }
}

Answer 1

You can do that with ajax. In order to do that, you need to implement ajax client function on frontend and a handler for processing ajax request. In frontend you can use jquery for ajax operations;

setInterval(function() {
    $.get( "handler.php", function( data ) {
      // You can use data. It is in json format. 
      // Ex: alert(data.message) . "message" is one of the 
      // fields of returned array in php handler file
    }); 
}, 3000);

handler.php

<?php
    $object = new Messages();
    $result = $object->ShowMessage($nick); 
    // I assume this returns array. 
    // Ex: array("type" => "error", "message" => "Error occured on feed");
    echo json_encode($result);
?>

Update: If you do not want to use json data

Update your code like below. Only use echo, you do not need to return json data.

public function ShowMessage() {

    $st = $this->db->prepare("SELECT * FROM bericht");
    $st->execute();
    if($st->rowCount() == 0){
        echo 'There is no message jet!';
    }  

        foreach ($st as $bericht){
        $uid = $bericht['uid'];

        $nick = $this->db->prepare("SELECT * FROM users WHERE id=?");
        $nick->bindParam(1, $uid);
        $nick->execute();

            foreach($nick as $name) {   

            $image = $name['foto'];

        if($image == 'nophoto.jpg'){
        echo '<img src="image/nophoto.jpg" width="60px" height="30px">';

        } else {
        echo '<img src="image/'; echo $image.'"'; echo ' width="60px" height="30px">';
        }
        echo $name['name'] .': ';
        echo $bericht['message'].' <br> ';

    }

    }
}

and in js;

setInterval(function() {
    $.get( "handler.php", function( data ) {
      // alert(data);
    }); 
}, 3000);