add_theme_support( 'infinite-scroll', array(
    'container'  => 'content',
    'footer' => false,
    'render' => 'vividflow_infscroll_render',
    'wrapper' => 'post_summaries',
    'posts_per_page' => 12,
    'type' => 'scroll'
) );

function setupPostSummaries(counter) {
    jQuery('.infinite-view-'+counter).doSomething();
}

<script type="text/javascript">setupPostSummaries(<?php the_counter(); ?>);</script>

<?php
/* Plugin Name: Infinite Scroll Counter Script */
add_action( 'wp_enqueue_scripts', 'wpse88834_add_script' );
function wpse88834_add_script()
{
    wp_enqueue_script(
        'wpse_counter',
        plugin_dir_url( __FILE__ ).'js/counter.js',
        array( 'jquery' ), // the infinte scroll script should also be added as dependency
        filemtime( plugin_dir_path( __FILE__ ).'js/counter.js' ),
        true
    );
    wp_localize_script(
        'wpse_counter',
        'wpse_counter_obj',
        array(
            'numberposts'    => $GLOBALS['wp_query']->numberposts,
            'found_posts'    => $GLOBALS['wp_query']->found_posts,
            'posts_per_page' => $GLOBALS['wp_query']->posts_per_page,
        )
    );
}

/* Inside ~/js/counter.js */
jQuery( document ).ready( function($) {
    /* wpse_counter_obj.numberposts */
    wpse_counter_obj.found_posts
    wpse_counter_obj.posts_per_page
    // Current
    var post_count_curr = 0;
    post_count_curr  += wpse_counter_obj.found_posts;
    console.log( post_count_curr  );
} );

function setupPostSummaries() {
    jQuery('.post_summaries').last().doSomething();
}

$curPage = (get_query_var('paged') ? get_query_var('paged') : 1) + 1;