Hi I’m trying to display post by author on author.php but I can’t get the author ID. domain.com/author/user_23/ ( display post from that user )

JQuery

    jQuery('#menu_posts').click(function(){
    $.ajax({
        type        : 'GET',
        url         : '/wp-admin/admin-ajax.php',
        dataType    : 'html',
        data        : { action: 'user_posts' },
        success : function(data){
                  $('#user-tab').html(data);
            },
            error: function(data){  
                alert("Error!");
                return false;
            }
        });
    });

Function

add_action('wp_ajax_user_posts', 'user_posts');
add_action('wp_ajax_nopriv_user_posts', 'user_posts');

function user_posts() {
    $args = array(
        'author'                 => $curauth->ID,
        'orderby'                => 'asc',
        'post_type'              => 'post',
        'posts_per_page'         => 10
    );
    $get_posts_query = new WP_Query( $args );
        while ( $get_posts_query->have_posts() ) : $get_posts_query->the_post() ?>

            (( html here ))

    <?php
    endwhile;
    die();
}

author.php

<?php $curauth = (get_query_var('author_name')) ? get_user_by('slug', get_query_var('author_name')) : get_userdata(get_query_var('author')); ?>