php insert string(a) at multiple positions in string b and concatenate the string-CodePudding

I've been working on a solution but my logic isn't quite there yet.

I'm looking to insert string A at multiple positions (positions from an array) into string B.

The array of positions variable is a strpos() return value[].

String B must be concatenated with itself so it contains the original string but with the new string A inserted at in multiple places.

Here's the logic so far:

    function add_submenu_back_item( $items, $args ){
        if( 'top-menu' == $args->theme_location ){
                $menu_item_back = '<a ><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor"  viewBox="0 0 16 16">
                <path fill-rule="evenodd" d="M12 8a.5.5 0 0 1-.5.5H5.707l2.147 2.146a.5.5 0 0 1-.708.708l-3-3a.5.5 0 0 1 0-.708l3-3a.5.5 0 1 1 .708.708L5.707 7.5H11.5a.5.5 0 0 1 .5.5z"/>
              </svg></a>';
                $subMenuPos = strpos($items, 'sub-menu');
                $new_items = '';
                $arrayPos = strpos_all( $items, 'sub-menu' );
                $offset = 10;
                $values;
                for ($i = 0; $i <= count($arrayPos) - 1; $i  ) {
                        // $new_items = substr_replace($items, $menu_item_back, $arrayPos[$i]   $offset, 0);
                        echo substr_replace($items, $menu_item_back, $arrayPos[$i]   $offset, 0);
                }
                
        }
        return ''; // testing mode, should be $new_items but doesnt seem to output the inserted value
} 
add_filter( 'wp_nav_menu_items', 'add_submenu_back_item', 10, 2 );

What I think the logic should express:

substr() Get the current startPos and endPos to cut out of the string.
Add the insert value to the end of substr() value.
if we already have a substr() value then add the new substr() with the insert value to the last one.
repeat this logic until for loop ends.

I'm trying to insert the $menu_item_back into $menu_items. $items is a string representing HTML menu navigation.

At the moment it's returning a repeated list $menu_items.

CodePudding user response：

I decided to use JavaScript for this solution. It was easier to access the DOM elements as needed and is a better way to solve this solution since it's Frontend dev and not server-side dev.

Code:

// create go-back element button
  var goBackEl = document.createElement('li');
  goBackEl.innerHTML = '<a  href="#"><svg xmlns="http://www.w3.org/2000/svg" width="30" height="30" fill="#FFFFFF"  viewBox="0 0 16 16"><path fill-rule="evenodd" d="M12 8a.5.5 0 0 1-.5.5H5.707l2.147 2.146a.5.5 0 0 1-.708.708l-3-3a.5.5 0 0 1 0-.708l3-3a.5.5 0 1 1 .708.708L5.707 7.5H11.5a.5.5 0 0 1 .5.5z"/></svg></a>';

// add go-back button to sub-menu as the first child
  submenuEl.prepend( goBackEl );