Get posts with ajax

Option 1

The simple way – return all the posts in JSON format and loop through them in JavaScript

PHP:

function get_ajax_posts() {
    // Query Arguments
    $args = array(
        'post_type' => array('products'),
        'post_status' => array('publish'),
        'posts_per_page' => 40,
        'nopaging' => true,
        'order' => 'DESC',
        'orderby' => 'date',
        'cat' => 1,
    );

    // The Query
    $ajaxposts = get_posts( $args ); // changed to get_posts from wp_query, because `get_posts` returns an array

    echo json_encode( $ajaxposts );

    exit; // exit ajax call(or it will return useless information to the response)
}

// Fire AJAX action for both logged in and non-logged in users
add_action('wp_ajax_get_ajax_posts', 'get_ajax_posts');
add_action('wp_ajax_nopriv_get_ajax_posts', 'get_ajax_posts');

JavaScript:

$.ajax({
    type: 'POST',
    url: '<?php echo admin_url('admin-ajax.php');?>',
    dataType: "json", // add data type
    data: { action : 'get_ajax_posts' },
    success: function( response ) {
        $.each( response, function( key, value ) {
            console.log( key, value ); // that's the posts data.
        } );
    }
});

Option 2

Get HTML content and print it to the screen.

PHP:

function get_ajax_posts() {
    // Query Arguments
    $args = array(
        'post_type' => array('products'),
        'post_status' => array('publish'),
        'posts_per_page' => 40,
        'nopaging' => true,
        'order' => 'DESC',
        'orderby' => 'date',
        'cat' => 1,
    );

    // The Query
    $ajaxposts = new WP_Query( $args );

    $response="";

    // The Query
    if ( $ajaxposts->have_posts() ) {
        while ( $ajaxposts->have_posts() ) {
            $ajaxposts->the_post();
            $response .= get_template_part('products');
        }
    } else {
        $response .= get_template_part('none');
    }

    echo $response;

    exit; // leave ajax call
}

// Fire AJAX action for both logged in and non-logged in users
add_action('wp_ajax_get_ajax_posts', 'get_ajax_posts');
add_action('wp_ajax_nopriv_get_ajax_posts', 'get_ajax_posts');

JavaScript:

   $.ajax({
        type: 'POST',
        url: '<?php echo admin_url('admin-ajax.php');?>',
        dataType: "html", // add data type
        data: { action : 'get_ajax_posts' },
        success: function( response ) {
            console.log( response );

            $( '.posts-area' ).html( response ); 
        }
    });

In the second example, change the .posts-area selector to the one you want to print in.

The console.log is just that you will be able to see the returning information from the AJAX call in the console. You should remove it after you finished.