Wordpress - AJAX Load More Steps

wp-ajax-loadmore.md

Step 1. Load more button

<?php
global $wp_query; // you can remove this line if everything works for you
 
// don't display the button if there are not enough posts
if (  $wp_query->max_num_pages > 1 )
	echo '<div class="misha_loadmore">More posts</div>'; // you can use <a> as well
?>

Step 2. Enqueue jQuery and myloadmore.js. Pass query parameters to the script.

function misha_my_load_more_scripts() {
 
	global $wp_query; 
 
	// In most cases it is already included on the page and this line can be removed
	wp_enqueue_script('jquery');
 
	// register our main script but do not enqueue it yet
	wp_register_script( 'my_loadmore', get_stylesheet_directory_uri() . '/myloadmore.js', array('jquery') );
 
	// now the most interesting part
	// we have to pass parameters to myloadmore.js script but we can get the parameters values only in PHP
	// you can define variables directly in your HTML but I decided that the most proper way is wp_localize_script()
	wp_localize_script( 'my_loadmore', 'misha_loadmore_params', array(
		'ajaxurl' => site_url() . '/wp-admin/admin-ajax.php', // WordPress AJAX
		'posts' => json_encode( $wp_query->query_vars ), // everything about your loop is here
		'current_page' => get_query_var( 'paged' ) ? get_query_var('paged') : 1,
		'max_page' => $wp_query->max_num_pages
	) );
 
 	wp_enqueue_script( 'my_loadmore' );
}
 
add_action( 'wp_enqueue_scripts', 'misha_my_load_more_scripts' );

Step 3. myloadmore.js – what is inside?

Option 1. Load More button

jQuery(function($){
	$('.misha_loadmore').click(function(){
 
		var button = $(this),
		    data = {
			'action': 'loadmore',
			'query': misha_loadmore_params.posts, // that's how we get params from wp_localize_script() function
			'page' : misha_loadmore_params.current_page
		};
 
		$.ajax({
			url : misha_loadmore_params.ajaxurl, // AJAX handler
			data : data,
			type : 'POST',
			beforeSend : function ( xhr ) {
				button.text('Loading...'); // change the button text, you can also add a preloader image
			},
			success : function( data ){
				if( data ) { 
					button.text( 'More posts' ).prev().before(data); // insert new posts
					misha_loadmore_params.current_page++;
 
					if ( misha_loadmore_params.current_page == misha_loadmore_params.max_page ) 
						button.remove(); // if last page, remove the button
 
					// you can also fire the "post-load" event here if you use a plugin that requires it
					// $( document.body ).trigger( 'post-load' );
				} else {
					button.remove(); // if no data, remove the button as well
				}
			}
		});
	});
});

Option 2. No button, just load posts on scroll

jQuery(function($){
	var canBeLoaded = true, // this param allows to initiate the AJAX call only if necessary
	    bottomOffset = 2000; // the distance (in px) from the page bottom when you want to load more posts
 
	$(window).scroll(function(){
		var data = {
			'action': 'loadmore',
			'query': misha_loadmore_params.posts,
			'page' : misha_loadmore_params.current_page
		};
		if( $(document).scrollTop() > ( $(document).height() - bottomOffset ) && canBeLoaded == true ){
			$.ajax({
				url : misha_loadmore_params.ajaxurl,
				data:data,
				type:'POST',
				beforeSend: function( xhr ){
					// you can also add your own preloader here
					// you see, the AJAX call is in process, we shouldn't run it again until complete
					canBeLoaded = false; 
				},
				success:function(data){
					if( data ) {
						$('#main').find('article:last-of-type').after( data ); // where to insert posts
						canBeLoaded = true; // the ajax is completed, now we can run it again
						misha_loadmore_params.current_page++;
					}
				}
			});
		}
	});
});

Step 4. wp_ajax_

function misha_loadmore_ajax_handler(){
 
	// prepare our arguments for the query
	$args = json_decode( stripslashes( $_POST['query'] ), true );
	$args['paged'] = $_POST['page'] + 1; // we need next page to be loaded
	$args['post_status'] = 'publish';
 
	// it is always better to use WP_Query but not here
	query_posts( $args );
 
	if( have_posts() ) :
 
		// run the loop
		while( have_posts() ): the_post();
 
			// look into your theme code how the posts are inserted, but you can use your own HTML of course
			// do you remember? - my example is adapted for Twenty Seventeen theme
			get_template_part( 'template-parts/post/content', get_post_format() );
			// for the test purposes comment the line above and uncomment the below one
			// the_title();
 
 
		endwhile;
 
	endif;
	die; // here we exit the script and even no wp_reset_query() required!
}
 
 
 
add_action('wp_ajax_loadmore', 'misha_loadmore_ajax_handler'); // wp_ajax_{action}
add_action('wp_ajax_nopriv_loadmore', 'misha_loadmore_ajax_handler'); // wp_ajax_nopriv_{action}