Proper way to load a single post via Ajax?

I’m loading single posts via Ajax into a div that I have set up on my index page. Everything is working fine in this regard. I want to use history.js to push/pop the state so if users enter example.com/my-post into the address bar, it loads up the index page with the post already loaded in the div. That is where the problem lies.

This is a simplified version of the function I’m using (the actual also includes a slide):

function my_load_ajax_content () {

    $args = array(
        'p' => $_POST['post_id'],
        'post_type' => 'projects'
        );

    $post_query = new WP_Query( $args );
    while( $post_query->have_posts() ) : $post_query->the_post(); ?>

    <div class="post-container">
        <div id="project-content">
            <?php the_title( '<h1 class="entry-title">', '</h1>' ); ?>
            <?php the_content(); ?>
        </div>
    </div><!-- .post-container -->

    <?php
    endwhile;
    wp_die();
}

add_action ( 'wp_ajax_nopriv_load-content', 'my_load_ajax_content' );
add_action ( 'wp_ajax_load-content', 'my_load_ajax_content' );

This is how I’m calling it:

$('.post-link').on('click', function(e) {
    e.preventDefault();

    var post_id = $(this).data('id'), // data-id attribute for .post-link
        projectTitle = $(this).data('title'), // data-title attribute for .post-link
        projectSlug = $(this).data('slug'), // data-slug attribute for .post-link
        ajaxURL = site.ajaxurl; // Ajax URL localized from functions.php

    $.ajax({
        type: 'POST',
        url: ajaxURL,
        context: this,
        data: {'action': 'load-content', post_id: post_id },
        success: function(response) {
            $('#project-container').html(response);
            return false;
        }
    });
});

Here is the loop

<?php $home_query = new WP_Query('post_type=projects');

while($home_query->have_posts()) : $home_query->the_post(); ?>

    <article class="project">
        <?php the_post_thumbnail( 'home-thumb' ); ?>
        <div class="overlay">
            <a class="post-link expand" href="https://wordpress.stackexchange.com/questions/175865/<?php the_permalink(); ?>" data-id="<?php the_ID(); ?>" data-title="<?php the_title(); ?>" data-slug="<?php global $post; echo $post->post_name; ?>">+</a>
        </div>
    </article>

<?php endwhile; ?>
<?php wp_reset_postdata(); // reset the query ?>

I’m wondering if I’m going about this the wrong way. I’m confused and a part of me is thinking that I should put all the html into my single template and call that from the Ajax function. But then I don’t exactly know how that would work either because if the user enters example.com/my-post into their browser, it’ll only load the single post without all of the html on the index page. I hope I’m explaining this correctly. Can someone show me how it’s done?

Here is my view: Load it inside your single.php why use ajax at all?
Google wont be able to see this (using most crawlers).

In any case – here is the right way to return the data…
please note that you can use get_post or wp_query. up tp you.

JS Part:

   jQuery(document).ready(function($) {
    $.post(ajax_object.ajaxurl, {
        action: 'my_load_ajax_content ',            
        post_id: post_id  // << should grab this from input...

    }, function(data) {

        var $response   =   $(data);
        var postdata    =   $response.filter('#postdata').html();

        $('.TARGETDIV').html(postdata);
    });
});

PHP Part:

function my_load_ajax_content () {

    $pid        = intval($_POST['post_id']);
    $the_query  = new WP_Query(array('p' => $pid));

    if ($the_query->have_posts()) {
        while ( $the_query->have_posts() ) {
            $the_query->the_post();

            $data="
            <div class="post-container">
                <div id="project-content">
                    <h1 class="entry-title">".get_the_title().'</h1>
                    <div class="entry-content">'.get_the_content().'</div>
                </div>
            </div>  
            ';

        }
    } 
    else {
        echo '<div id="postdata">'.__('Didnt find anything', THEME_NAME).'</div>';
    }
    wp_reset_postdata();


    echo '<div id="postdata">'.$data.'</div>';
}

add_action ( 'wp_ajax_nopriv_load-content', 'my_load_ajax_content' );
add_action ( 'wp_ajax_load-content', 'my_load_ajax_content' );

Hope this helps.
again, i wouldnt recommend doing that but… this should work.

REVISION FOR GET POST ON CLICK

first: the button / link – should be something like

<button class="get_project" data-postid="POSTID HERE!">PROJECT NAME</button>

second: the js code listening to a click:

jQuery(function($){

    $('.get_project').click(function() {

        var postid = $(this).attr('data-postid');

        $.post(ajax_object.ajaxurl, {
            action: 'my_load_ajax_content ',            
            postid: postid
        }, function(data) {
            var $response   =   $(data);
            var postdata    =   $response.filter('#postdata').html();
            $('.TARGETDIV').html(postdata);
        });

    })

});

The php code needs no changing – just set the data you need.