Get List of Directories in AWS S3 as array keys. Nested subfolders

s3_dirs.php

<?php 
require_once( __DIR__ . '/aws/aws-autoloader.php' );
use Aws\S3\S3Client;

define( 'AWS_S3', [
    'key' => '',
    'secret' => '',
    'bucket' => ''
]);

function get_dirs() {
    $s3 = S3Client::factory([
        'credentials' => [
            'key' => AWS_S3[ 'key' ],
            'secret' => AWS_S3[ 'secret' ],
        ],
        'region'  => 'us-east-1',
        'version' => 'latest'
    ]);

    $objects = $s3->getIterator( 'ListObjects', [ 'Bucket' => AWS_S3[ 'bucket' ] ] );
    $dirs = [];
    foreach( $objects as $ob ) {
        if( preg_match( '/^.*\/$/', $ob[ 'Key' ] ) ) {
            $split = explode( '/', $ob[ 'Key' ] );
            $dirs = nest_dir( $dirs, $split );
        }
    }
    return $dirs;
}

function nest_dir( $ref, $dirs ) {
    $dirs = array_filter( $dirs );
    foreach( $dirs as $index => $dir ) {
        $parent = @$dirs[ $index - 1 ];

        if( $parent && isset( $ref[ $parent ] ) ) {
            $ref[ $parent ][ $dir ] = nest_dir( [], array_slice( $dirs, $index + 1 ) );
            continue;
        }
        if( !$parent || ( $parent && array_search( $parent, $dirs ) === 0 ) )
            $ref[ $dir ] = [];
    }
    return $ref;
}

print_r( get_dirs() );

I use this jQuery to create unordered list elements, nested for subfolders

function show_dirs( ele, folders, prefix ) {
    jQuery.each( folders, function( key, value ) {
        prefix = ( prefix ? prefix + '/' + key : key )
        ele.append( '<li data-key="' + key + '" class="folder" data-prefix="' + prefix + '">' + key + '</li>' )
        if( Object.values( value ).length ) {
            var id = getRandomInt( 100, 999 )
            ele.find( 'li[data-key="' + key + '"]' ).append( '<ul id="folder_' + id + '" class="folders"></ul>' )
            show_dirs( ele.find( '#folder_' + id ), value, prefix )
        }
        prefix = ''
    })
}

<ul id="dirs"></ul>

show_dirs( $( '#dirs' ), json_object, '' )