Inserter allows you to create custom templates from your dashboard and insert the in your pages, replacing a CSS selector of your choosing.
You can use the
WordPress Templates Interpolation for
underscore.js and include JS-based logic in your templates.
You can expose data using the REST API, using the global
$post
object, or provide your own JSON-formatted data.
To see the available data, you can add this line in your template and then check the console when your site loads:
<# console.log( data ); #>
You can read more about how to use the plugin on
https://aristath.github.io/wordpress/introducing-wordpress-inserter-plugin.
Simply install as a normal WordPress plugin and activate.