I want to add class to the menu item link in wordpress

Hello I am converting a HTML5 template to wordpress. In the html template, i have added classes to the <a> links of menu items which have sub menus. I know we can add classes to the menu item’s <li> in wordpress but i want to add class in the <a> in the <li> in wordpress menu item. So currently wordpress output is

<ul class="nav navbar-nav pull-right">
<li id="menu-item-4" class="menu-item menu-item-type-custom menu-item-object-custom current-menu-item current_page_item menu-item-home menu-item-has-children primary menu-item-4"><a href="https://localhost/wordpress/">Home</a>
<ul class="subMenu" style="display: none;">
	<li id="menu-item-5" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-has-children menu-item-5"><a href="https://localhost/wordpress/sample-page/">Sample Page</a></li>
	</ul>
</li>

<li id="menu-item-8" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-8"><a href="#">Link</a></li>

<li id="menu-item-9" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-9"><a href="#">Link</a></li>
</ul>

and the output i want is

<ul class="nav navbar-nav pull-right">
<li id="menu-item-4" class="menu-item menu-item-type-custom menu-item-object-custom current-menu-item current_page_item menu-item-home menu-item-has-children primary menu-item-4"><a class="firstLevel hasSubMenu" href="https://localhost/wordpress/">Home</a>
<ul class="subMenu" style="display: none;">
	<li id="menu-item-5" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-has-children menu-item-5"><a href="https://localhost/wordpress/sample-page/">Sample Page</a></li>
</a></li>
<li id="menu-item-8" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-8"></a><a href="#">Link</a>

<li id="menu-item-9" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-9"><a href="#">Link</a>

As you can see in the output which i want there is “Home” menu item, I have added class="firstLevel hasSubMenu" in the <a> for the “Home” menu item
<li>.

I have this code added in my theme’s “functions.php” for adding class to the menu items which have sub menus <li>

function menu_set_dropdown( $sorted_menu_items, $args ) {
    $last_top = 0;
    foreach ( $sorted_menu_items as $key => $obj ) {
        // it is a top lv item?
        if ( 0 == $obj->menu_item_parent ) {
            // set the key of the parent
            $last_top = $key;
        } else {
            $sorted_menu_items[$last_top]->classes['hasSubMenu'] = 'hasSubMenu';
        }
    }
    return $sorted_menu_items;
}
add_filter( 'wp_nav_menu_objects', 'menu_set_dropdown', 10, 2 );

Any help will be highly appreciated.