How to pass parameter to php while calling it from javascript

Question

I am calling a PHP script from JavaScript. Whenever my function is called, I want to set tag=image. How can I do that?

function httpGetAsync(theUrl, callback) {
    var xmlHttp = new XMLHttpRequest();
    xmlHttp.onreadystatechange = function() { 
        if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {
            callback(xmlHttp.responseText);
        }
    }
    xmlHttp.open("POST", theUrl, true); 
    xmlHttp.send(null);
}

httpGetAsync('storeImage.php');

The file storeImage.php looks like

<?php
$img = $_POST['tag'];
 $folderPath = "C:/xampp/htdocs/";

    $image_parts = explode(";base64,", $img);
    $image_type_aux = explode("image/", $image_parts[0]);
    $image_type = $image_type_aux[1];

    $image_base64 = base64_decode($image_parts[1]);
    $fileName = 't' . '.jpeg';

    $file = $folderPath . $fileName;
    file_put_contents($file, $image_base64);

    print_r($fileName);
    $command = escapeshellcmd("python C:/xampp/htdocs/generate_graph.py");
    $output = shell_exec($command);
    echo $output;
?>

Well, you have `xmlHttp.open("GET"` and then `$_POST['tag'];` so first you need to decide whether you want to be making a POST request or a GET request and then use the same term on both sides. — Patrick Q, Nov 22 '19 at 13:04
Possible duplicate of [POST from XMLHttp with parameters](https://stackoverflow.com/questions/7071544/post-from-xmlhttp-with-parameters) — Patrick Q, Nov 25 '19 at 14:34
Also https://stackoverflow.com/questions/9713058/send-post-data-using-xmlhttprequest — Patrick Q, Nov 25 '19 at 14:35

score 0 · Answer 1 · answered Nov 22 '19 at 13:07

There are conflicts,

In your xmlHttpRequest you are triggering a GET Request. But, In your storeImage.php, You are accessing POST data.
The httpGetAsync functions get 2 parameters (theUrl, callback), But when you call the function, You only pass the url.

Correct Example Code

function httpGetAsync(theUrl){
    var xmlHttp = new XMLHttpRequest();
    xmlHttp.onreadystatechange = function() { 
        if (xmlHttp.readyState == 4 && xmlHttp.status == 200)
          alert(xmlHttp.responseText);
        }
    xmlHttp.open("GET", theUrl + "getData=hello", true); 
    xmlHttp.send();
}

<?php

  echo $_GET['getData'];

?>

Please Take a tour https://www.w3schools.com/php/php_ajax_php.asp

i have tried with both get and post .but it is not working.i have uploaded my whole code.can you tell me where is the problem? — Shafat Ahmed, Nov 25 '19 at 11:16

How to pass parameter to php while calling it from javascript

1 Answers1