How to use page specific javascript using the starter-blog template using asset rev plugin?

Use the rev function provided by the plugin to get the path to your JS file (relative to the asset base path) and register it with the {% js %} tag:

{% js rev('js/foobar.js') at head with { defer: true } %}

Another option that I like to use is to declare a block in the base template and then extend it the page specific template:

{# templates/_private/layout/index.html #}
{% block assets %}
    <link rel="stylesheet" href="{{ rev('main.css') }}">
{% endblock %}

{# templates/_private/your-page.html #}
{% extends '_private/layout/index.html' %}

{% block assets %}
    {{ parent() }}
    <script src="{{ rev('js/foobar.js') }}" defer>
{% endblock %}