Csrf token in ajax request

Yii 2.0 General Discussions
1

In Yii, How pass csrf token in ajax request, getting following error
Unable to verify data submission

2

From the api docs:

In JavaScript, you may get the values of $csrfParam and $csrfToken via yii.getCsrfParam() and yii.getCsrfToken(), respectively. The yii\web\YiiAsset asset must be registered. You also need to include CSRF meta tags in your pages by using yii\helpers\Html::csrfMetaTags().

Within the page:

<?php
use yii\helpers\Html;
use yii\web\YiiAsset;

YiiAsset::register($this);
?>
<?php $this->beginPage() ?>
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <?= Html::csrfMetaTags() ?>
    <?php $this->head() ?>
</head>
<body>
<?php $this->beginBody() ?>
<?php $this->endBody() ?>
</body>
</html>
<?php $this->endPage() ?>