Dynamic possible ajax style menu

This would need to be custom, and would probably need to use ajax yes (endpoint to return terms of X).

So select top level, ajax call, append 2nd level to form.

I had an almost working solution that is basically this code:

in the functions.php of the child theme:

function implement_ajax() {
if(isset($_POST['main_catid']))
			{
			$categories=  get_categories('child_of='.$_POST['main_catid'].'&hide_empty=0');
			  foreach ($categories as $cat) {
				$option .= '<option value="'.$cat->term_id.'">';
				$option .= $cat->cat_name;
				$option .= ' ('.$cat->category_count.')';
				$option .= '</option>';
			  }
			  echo '<option value="-1" selected="selected">Sub Categories</option>'.$option;
			die();
			} // end if
}
add_action('wp_ajax_my_special_ajax_call', 'implement_ajax');
add_action('wp_ajax_nopriv_my_special_ajax_call', 'implement_ajax');//for users that are not logged in.

if ( function_exists('register_sidebar') ) {
	register_sidebar(array(
		'before_widget' => '<li id="%1$s" class="widget %2$s">',
		'after_widget' => '</li>',
		'before_title' => '<h2 class="widgettitle">',
		'after_title' => '</h2>',
	));
}

For the job-submit.php template I added the following

<script type="text/javascript">
$(function(){
			$('#main_cat').change(function(){
					var $mainCat=$('#main_cat').val();

					// call ajax
					 $("#sub_cat").empty();
												$.ajax({
														url:"<?php bloginfo('wpurl'); ?>/wp-admin/admin-ajax.php",
														type:'POST',
														data:'action=my_special_ajax_call&main_catid=' + $mainCat,

												   success:function(results)
													   {
														//  alert(results);
														$("#sub_cat").removeAttr("disabled");
														  $("#sub_cat").append(results);
														}
												   });

										  }
										  );
});
										  </script>

wp_dropdown_categories('show_count=0&selected=-1&hierarchical=1&depth=1&hide_empty=0&exclude=1&show_option_none=Main Categories&name=main_cat');
?>

This got us a start but now we have made some changes that look like this.

$category_args = array(
		'orderby' => 'name',
		'order' => 'ASC',
		'hide_empty' => false,
		'fields' =>	'id=>name',
	);
	$category_args1 = $category_args;
	$category_args1['parent'] = 0;
	$job_categories1 = get_terms('job_listing_category', $category_args1);

    $fields['job']['_job_cat1'] = array(
        'label'     => __( 'Cat1', 'wp-job-manager' ),
        'type'      => 'select',
        'options' 	=> $job_categories1,
        'required'    => true,
        'placeholder' => '',
        'priority'    => 3.1,
    );

	$category_args2 = $category_args;
	/*$category_args2['parent'] = 1;*/
	$job_categories2 = get_terms('job_listing_category', $category_args2);

    $fields['job']['_job_cat2'] = array(
        'label'     => __( 'Cat2', 'wp-job-manager' ),
        'type'      => 'select',
        'options' 	=> $job_categories2,
        'required'    => true,
        'placeholder' => '',
        'priority'    => 3.2,
    );

	$category_args3 = $category_args;
	/*$category_args3['parent'] = 2;*/
	$job_categories3 = get_terms('job_listing_category', $category_args3);

    $fields['job']['_job_cat3'] = array(
        'label'     => __( 'Cat3', 'wp-job-manager' ),
        'type'      => 'select',
        'options' 	=> $job_categories3,
        'required'    => true,
        'placeholder' => '',
        'priority'    => 3.3,
    );

    return $fields;
}

/*
	wp_dropdown_categories('show_count=0&selected=-1&hierarchical=1&depth=1&hide_empty=0&exclude=1&show_option_none=Main Categories&name=main_cat&taxonomy=job_listing_category');
*/

function implement_ajax() {
    if(isset($_POST['main_catid']))
    {
        $categories=  get_categories('child_of='.$_POST['main_catid'].'&hide_empty=0&taxonomy=job_listing_category');
            foreach ($categories as $cat) {
            $option .= '<option value="'.$cat->term_id.'">';
            $option .= $cat->cat_name;
            $option .= ' ('.$cat->category_count.')';
            $option .= '</option>';
        }
        echo '<option value="-1" selected="selected">Sub Categories</option>'.$option;
        die();
    } // end if
}
add_action('wp_ajax_my_special_ajax_call', 'implement_ajax');

//add_action('wp_ajax_nopriv_my_special_ajax_call', 'implement_ajax');//for users that are not logged in.

if ( function_exists('register_sidebar') ) {
    register_sidebar(array(
        'before_widget' => '<li id="%1$s" class="widget %2$s">',
        'after_widget' => '</li>',
        'before_title' => '<h2 class="widgettitle">',
        'after_title' => '</h2>',
    ));
}

// Add our own function to filter the fields
add_filter( 'submit_resume_form_fields', 'custom_submit_resume_form_fields' );

I am kind of lost by these changes but if you can guide me in a good direction I would appreciate it. Also if you just know of someone we can hire to do this right we are willing to go that rout. I posted in the wordpress job section but got so many low quality responses I have not been able to effectivly sort through them all.

You may want to look into one of these services:

https://jobs.wordpress.net/

https://studio.envato.com/

https://codeable.io/

… or some development shops:

https://growdevelopment.com/

https://wisdmlabs.com/

https://tinygiantstudios.co.za/

Thanks!

Thank you for the resources I will check into them.