Creating Google Graph in Wordpress plugin with data from PHP

Question

I want to create a Google graph in Wordpress, using data that I collect from Google Datastore with a Wordpress plugin (i.e. with PHP). I have followed this, but getting the code to work in Wordpress requires a little more. I have a Javascript file, and a PHP file (the Wordpress plugin, where I want the graph to be displayed).

Javascript is working and Ajax works when sending data from Javascript to PHP, so I have at least made the necessary adjustments in Wordpress for this basic functionality. But I need to get the data from PHP to the Javascript functions for drawing the graph, which isn't working. (The Ajax error function gets called.)

javascript.js

createGraph();

function createGraph() {
    google.charts.load('current', {packages: ['corechart', 'line']});
    google.charts.setOnLoadCallback(drawGraph);
}

function drawGraph() {
    jQuery(document).ready(function($) {
    var jsonData = null;
    var json = jQuery.ajax({
        url: ajax_object.ajax_url,
        data: {
        'action': 'ajax_request'
        },
        dataType:"json",
        async: false,
        success:function(data) {
            console.log(data);
            jsonData = data;
            var data = new google.visualization.DataTable(jsonData);        

            // Instantiate and draw our chart, passing in some options.
            var options = {
                hAxis: {
                    title: 'Time',
                    logScale: true
                },
                vAxis: {
                    title: 'Popularity',
                    logScale: false
                },
                colors: ['#a52714', '#097138']
            };

            var chart = new google.visualization.LineChart(document.getElementById('chart_div'));
            chart.draw(data, options);
        },
        error: function(errorThrown){
            console.log(data);
        }
    });
    }).responseText;
}

plugin.php

...

// Getting jQuery/Javascript/Ajax to work
function my_enqueue() {
   // Only works on specific page
   if(is_page (151)) {
      wp_enqueue_script('javascript', plugins_url() . '/embed_cloud_datastore/js/javascript.js', array('jquery'), '1.0.0', true);

      // We can define the AJAX url with using wp_localize_script
      wp_localize_script( 'javascript', 'ajax_object',
            array( 'ajax_url' => admin_url( 'admin-ajax.php' ) ) );
   }
}
add_action('wp_enqueue_scripts', 'my_enqueue');
add_action( 'wp_ajax_ajax_request', 'ajax_request' );

function ajax_request() {

$table = array();
$table['cols'] = array(
    /* define your DataTable columns here
     * each column gets its own array
     * syntax of the arrays is:
     * label => column label
     * type => data type of column (string, number, date, datetime, boolean)
     */
    // I assumed your first column is a "string" type
    // and your second column is a "number" type
    // but you can change them if they are not
    array('label' => 'Date', 'type' => 'string'),
    array('label' => 'Variable', 'type' => 'number')
);

$rows = array();
$temp = array();
// each column needs to have data inserted via the $temp array
$temp[] = array('v' => "2019-08-26");
$temp[] = array('v' => (int) 3); 
$temp[] = array('v' => "2019-08-24");
$temp[] = array('v' => (int) 5); 
// insert the temp array into $rows
$rows[] = array('c' => $temp);


// populate the table with rows of data
$table['rows'] = $rows;

// encode the table as JSON
$jsonTable = json_encode($table);
echo $jsonTable;

// To return to the front page, always finish after echoing the desired content.
wp_die();
}

This test function works, i.e. sending from Javascript to PHP.

function testAjax() {
    jQuery(document).ready(function($) {
    //We'll pass this variable to the PHP function example_ajax_request
    var car = 'BMW';
    // This does the ajax request
    jQuery.ajax({
    url: ajax_object.ajax_url,
    data: {
        'action':'ajax_request',
        'car' : car
    },
    success:function(data) {
        // The OutPut after successfully receiving content
        console.log(data);
        window.alert("Working test function!");
    },
    error: function(errorThrown){
        console.log(errorThrown);
    }
    });
});
}

I am new to Ajax and I guess there is something in that code which is the problem. I seem to need the data: {'action': 'ajax-request'} for Wordpress, but this is for sending data if I have understood correctly. So where to put this when retrieving data?