Magento 2, error 'unserialize value' when using Ajax in phtml in admin page

Question

Using Magento 2, Ajax in phtml, Admin. I got an error while trying to request API by ajax from template of sale order page.

AJAX

<script type="text/javascript">
require(['jquery', 'domReady!'], function($){
    changeDriver = function () {
        var driverBase = 'https://127.0.0.1:445/index.php/rest/V1/driver'
        var data = {"orderId": "58", "driverId": "20"};
        $.ajax({
            showLoader: true,
            url: driverBase,
            type: "POST",
            data: data,
            dataType: 'json',
            contentType: "application/json; charset=utf-8"

        }).done(function (data) {
            console.log(data);
            $('#driver_detail').html('Driver chnaged.');

        }).fail(function (jqXhr) {
            console.log(jqXhr);
            $('#driver_detail').html('Cannot change driver.');
        });
    }
});
</script>

Header

**General**
Request URL: https://127.0.0.1:445/index.php/rest/V1/driver/?isAjax=true
Request Method: POST
Status Code: 400 Bad Request
Remote Address: 127.0.0.1:445
Referrer Policy: no-referrer-when-downgrade

**Request Payload**
orderId=58&driverId=20&form_key=AKlwzR4oQvfmyhzL

Error

{"message":"Decoding error: \nUnable to unserialize value.\n#0 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/framework/Webapi/Rest/Request/Deserializer/Json.php(64): Magento\Framework\Serialize\Serializer\Json->unserialize('orderId=58&driv...')\n#1 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/framework/Webapi/Rest/Request.php(141): Magento\Framework\Webapi\Rest\Request\Deserializer\Json->deserialize('orderId=58&driv...')\n#2 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/framework/Webapi/Rest/Request.php(199): Magento\Framework\Webapi\Rest\Request->getBodyParams()\n#3 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/module-webapi/Controller/Rest/InputParamsResolver.php(97): Magento\Framework\Webapi\Rest\Request->getRequestData()\n#4 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/module-webapi/Controller/Rest.php(322): Magento\Webapi\Controller\Rest\InputParamsResolver->resolve()\n#5 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/module-webapi/Controller/Rest.php(239): Magento\Webapi\Controller\Rest->processApiRequest()\n#6 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/framework/Interception/Interceptor.php(58): Magento\Webapi\Controller\Rest->dispatch(Object(Magento\Framework\App\Request\Http))\n#7 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/framework/Interception/Interceptor.php(138): Magento\Webapi\Controller\Rest\Interceptor->___callParent('dispatch', Array)\n#8 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/framework/Interception/Interceptor.php(153): Magento\Webapi\Controller\Rest\Interceptor->Magento\Framework\Interception\{closure}(Object(Magento\Framework\App\Request\Http))\n#9 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/generated/code/Magento/Webapi/Controller/Rest/Interceptor.php(39): Magento\Webapi\Controller\Rest\Interceptor->___callPlugins('dispatch', Array, Array)\n#10 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/framework/App/Http.php(135): Magento\Webapi\Controller\Rest\Interceptor->dispatch(Object(Magento\Framework\App\Request\Http))\n#11 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/vendor/magento/framework/App/Bootstrap.php(256): Magento\Framework\App\Http->launch()\n#12 /home/dev/Work/Web_Application/SVN/driver-mage/esh_www/index.php(39): Magento\Framework\App\Bootstrap->run(Object(Magento\Framework\App\Http))\n#13 {main}","trace":null}

Answer 1

<script>
    require(['jquery'], function($){            
        $.ajax({
            type: "POST",
            url: "http://127.0.0.1/m225/rest/V1/integration/admin/token",
            data: JSON.stringify({'username': 'admin', 'password': 'admin123'}),
            dataType: 'json',
            contentType: 'application/json',
            processData: false,
            success: function(response){
                console.log(response);
                console.log(JSON.stringify(response));
                document.write(JSON.stringify(response));
            },
            error: function(jqXHR, textStatus, errorThrown) {
                console.log(errorThrown);
            }
        });
    });
</script>

Please change data: data, with data: JSON.stringify(data),