[WordPress] Download User Email Addresses via JSON in WordPress

00-add-submenu-page.php

<?php
public function addSubmenuPage()
{
    \add_submenu_page(
        'tools.php',
        'Export Emails',
        'Export Emails',
        'manage_options',
        'acme-export-emails',
        'exportEmails'
    );
}

01-register-javascript.php

<?php

public function addJavaScript()
{
    if (!current_user_can('manage_options')) {
        return;
    }

    wp_enqueue_script(
        'acme-email-export-admin',
        $this->plugin_url . 'Emails/assets/scripts/exportEmail.js',
        array('jquery')
    );

    wp_localize_script(
        'acme-email-export-admin',
        'acme_email_export',
        array(
            'ajax_url' => admin_url('admin-ajax.php'),
            'security' => wp_create_nonce('acme-email-export-nonce')
        )
    );
}

02-click-handler.js

$('a[href="tools.php?page=acme-export-emails"]').on('click', function(evt){
    evt.preventDefault();
    _getEmailAddresses($(this));
});

03-get-email-addresses.js

var _getEmailAddresses = function($elem) {
    $.get(acme_email_export.ajax_url, {
        security:  acme_email_export.security,
        action:    'getEmailAddresses'
    }, function(response) {

        if ( '' === response ) {
            return;
        }
        // TODO...
    });
};

04-get-email-addresses.php

<?php
private function getUserResults()
{
    $query   = new \WP_User_Query(
        array(
            'role_in' => array('administrator','subscriber')
        )
    );
    return $query->get_results();
}

05-parse-email-results.php

<?php

private function getUserInfo($results)
{
    $user_info = array();
    foreach ($results as $result) {
        if (isset($result->user_email)) {
            array_push($user_info, $result->user_email);
        }
    }

    return $user_info;
}

06-write-json-to-disk.php

<?php

private function writeAddressesToDisk($addresses)
{
    $path = plugin_dir_path(__FILE__) . 'results.json';
    if (!file_exists($path)) {
        touch($path);
    }

    $handle = fopen($path, 'w');
    fwrite($handle, json_encode($addresses));
    fclose($handle);
}

07-get-email-addresses.php

<?php

public function getEmailAddresses()
{
    $this->writeAddressesToDisk(
        $this->getUserInfo(
            $this->getUserResults()
        )
    );

    echo plugin_dir_url(__FILE__) . 'results.json';
    die;
}

08-get-email-addresses.js

var _getEmailAddresses = function($elem) {
    $.get(acme_email_export.ajax_url, {
        security:  acme_email_export.security,
        action:    'getEmailAddresses'
    }, function(response) {

        if ( '' === response ) {
            return;
        }

        // Creates the element to download the file.
        $('<a/>')
            .attr('href', response)
            .attr('download', 'response.json')
            .attr('id', 'acme-download-emails')
            .text('Download')
            .attr('style', 'display:none')
            .appendTo($elem.parent());

        // Manually trigger clicking of the hidden element to download the file.
        $('#acme-download-emails')[0].click();
    });
};