If we take a look the Json config of xml layout on checkout page:
[![enter image description here][1]][1]
As we can see, we can add the custom content to `itemsBefore` area.
For example code:
**app/code/Vendor/Checkout/view/frontend/layout/checkout_index_index.xml**
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceBlock name="checkout.root">
<arguments>
<argument name="jsLayout" xsi:type="array">
<item name="components" xsi:type="array">
<item name="checkout" xsi:type="array">
<item name="children" xsi:type="array">
<item name="sidebar" xsi:type="array">
<item name="children" xsi:type="array">
<item name="summary" xsi:type="array">
<item name="children" xsi:type="array">
<item name="itemsBefore" xsi:type="array">
<item name="children" xsi:type="array">
<item name="testcustom" xsi:type="array">
<item name="component" xsi:type="string">Vendor_Checkout/js/view/summary/custom</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</argument>
</arguments>
</referenceBlock>
</body>
</page>
**app/code/Vendor/Checkout/view/frontend/web/js/view/summary/custom.js**
define(
[
'uiComponent'
],
function (Component) {
'use strict';
return Component.extend({
defaults: {
template: 'Vendor_Checkout/view/summary/custom'
}
});
}
);
**app/code/Vendor/Checkout/view/frontend/web/template/view/summary/custom.html**
<div>Test Test Here</div>
[1]: https://i.sstatic.net/QzzD3.png