WordPress post content content replacement

functions.php

add_filter('the_content', function($content) {
    $bindings = [
        '<img' => ['click: lightbox.show']
    ];
    
    foreach ($bindings as $tag => $directives) {
        $directive = sprintf('%s data-bind="%s" ', $tag, implode(', ', $directives));
        $content = str_replace($tag, $directive, $content);
        // <img data-bind="click: lightbox.show" 
    }
    
    return $content;
});