How to make a click on an element that can appear and disappear depending on clicking on different elements on the site?

Question

Google Chrome

I want to make a small extension for vk.com, but I started having problems almost immediately. There, many elements are created dynamically and I don’t know how to hang a handler on them.
manifest.json

{
  "content_scripts": [ {
    "css": [ "style.css" ],
    "js": [ "jquery-3.3.1.min.js", "content.js" ],
    "matches": [ "*://vk.com/*", "*://*.vk.com/*" ],
    "run_at": "document_end"
   } ],
   "icons": {
      "128": "icons/128x128.png",
      "16": "icons/16x16.png",
      "19": "icons/19x19.png",
      "38": "icons/38x38.png",
      "48": "icons/48x48.png"
   },
   "manifest_version": 2,
   "version": "1.0.1",
   "web_accessible_resources": [ "*.js" ]
}

jquery-3.3.1.min.js - respectively jquery
content.js library

$(function ($) {
  if( location.host == "vk.com" ) {
    // $("body").on("click", "...", function( e ) { alert('123'); }); - не работает, не цепляется событие
    $('...').click(function() { alert('123'); }); // работает, только если элемент на странице уже существует
  }
});

I've been suffering for several hours now, has anyone experienced this?