How do I trigger an “on change” event of another select element?

Question

I have two select elements. one for a property and one for a category. When I select property it goes to a function through ajax and return an array to other select elements (category) #option. I need to do is, when I select a property, the category elements first option should be selected and trigger that elements on change event.

Form

public function buildForm(
    array $form, 
    FormStateInterface $form_state, 
    $properties = [],
    $categories = [],
    $propertyContent = [],
    $isCorporate = false,
    $propertyId = null
) { 
    $propertyKey = null;

    if (!empty($form_state->getValue('property'))) {
        $propertyKey = $form_state->getValue('property');
    } else {
        $propertyKey = key($properties);
    }

    $form['property'] = [
        '#type'          => 'select',
        '#id'            => 'property',
        '#attributes'    => ['class' => ['form-control']],
        '#title'         => $this->t('Hotel'),
        '#options'       => $properties,
        '#default_value' => $propertyKey,
        '#ajax'          => [
            'callback'  => 'create_category_list',
            'event'     => 'change',
            'wrapper'   => 'category-type',
            'method'    => 'html'
        ],
        '#required'  => true,
        '#validated' => true,
    ];

    $form['category'] = [
        '#type'         => 'select',
        '#id'           => 'category',
        '#attributes'   => ['class' => ['form-control']],
        '#title'        => $this->t('Category'),
        '#options'      => $categoryList,
        '#ajax'         => [
            'callback'  => 'show_gallery_ajax',
            'event'     => 'change',
            'wrapper'   => 'gallery-images',
            'method'    => 'html',
            'progress'  => [
                'type'    => 'throbber',
                'message' => t('Loading gallery !'),
            ],
        ],
        '#prefix'        => '<div id ="category-type">',
        '#suffix'        => '</div>',
        '#default_value' => $defaultCategory,
        '#required'      => false,
        '#validated'     => true,
    ];

    return $form;
}