How to get a variable from PHP file using Ajax?

Question

I just started studying PHP and Ajax and I can't figure out how to bring a single variable from PHP file to my html file using Ajax. Can you please explain me how it works?

So far I understood that you create the request:

var xhttp = new XMLHttpRequest();

And that you send it to the server:

xhttp.open("GET", "demo_get.php", true);
xhttp.send();

Then you get the data from the PHP file using

xhttp.responseText

Now, I only want to send a variable from the server, for example

$name = "John"

How should my php code look like in order to send only that specific variable?

zanderwar · Accepted Answer · 2020-07-07 07:18:25Z

2

As a beginner, it would be a lot easier to use jQuery for your AJAX requests. I've been in this industry for over half my life and I still use it alot.

getstuff.php

header('Content-type: application/json');
echo json_encode(["FirstName" => "John"]);
exit;

jquery:

$.ajax({
    url: '/getstuff.php',
    success: function (response) {
        console.log(response);
        alert(response.FirstName);
    }
});

edited Jul 7, 2020 at 7:18

answered Jul 7, 2020 at 6:53

zanderwar

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1 Comment

Benni Over a year ago

PHP's header() function must be called like this: header('Content-Type: application/json');

Benni · Accepted Answer · 2020-07-07 07:24:31Z

I suggest using JSON as data interchange format, here is the javascript part:

let request = new XMLHttpRequest();

request.open('GET', 'demo_get.php', true);

request.onload = function() {
    if (this.status >= 200 && this.status < 400) {
        // Success
        let parsed_response = JSON.parse(this.response.trim());
        console.log(parsed_response.my_var);
    } else {
        // Error
        console.log(this.response);
    }
};
request.onerror = function() {
    console.log('Connection error!');
};
request.send();

The PHP part then would look like this:

<?php
header('Content-Type: application/json');
$my_response_data = ['my_var' => 'foo'];   
echo json_encode($my_response_data);
exit;

... and some useful info about XMLHttpRequest.responseText vs XMLHttpRequest.response

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