wordpress ajax callback example

wp_ajax_callback_example.php

<form id="search">
	<input type="hidden" name="action" value="custom_search" />
	<input type="text" id="texto" name="texto" />
	<input type="submit" value="submit" />
</form>
<div id="answer"></div>
<script type="text/javascript">
jQuery(function($){
	$("#search").submit(function(e){
		if( $("#search").hasClass("sending") ) return false;
		// if no sending yet, send
		e.preventDefault();
		// creamos un objeto con los inputs del form {name:value,...}
		var formData = $("#search").serialize();
		$("#search").addClass("sending");
		$.ajax({
			type: 'POST',
			url: '<?php echo admin_url( 'admin-ajax.php' ); ?>',
			data: formData,
			success: function(data, textStatus, jqXHR){
				$("#answer").html( data );
			},
			error: function(jqXHR, textStatus, errorThrown){
				$("#answer").html('ERROR');
				$("#search").removeClass("sending");
			}
		});
	});
});
</script>

<?php
/**********esto*va*en*tu*functions.php**********/
add_action( 'wp_ajax_custom_search', 'custom_search_callback' );
add_action( 'wp_ajax_nopriv_custom_search', 'custom_search_callback' );
function custom_search_callback(){
	$texto = sanitize_text_field($_REQUEST['texto']);
	if( !empty($texto) ){
		$taxonomy_arr = get_terms( 'taxonomy', array(
			'hide_empty' => 0,
			'order'=>'ASC',
			'search' => $texto
			) );
		//var_dump( $cats_number );
		foreach ($taxonomy_arr as $key => $taxonomy):
		?>
			<div><?php echo $taxonomy->name; ?></div>
		<?php
		endforeach
	}else{
		?>
		<div>Vacia</div>
		<?php
	}
	exit();
}
?>