The hackiest way to export/import namespaces between AEM instances without any external dependencies

exportNameSpaceCND.js

/**
 * EXPORT NAMESPACES
 * 1. Open http://localhost:4502/crx/explorer/ui/namespace_editor.jsp
 * 2. Open Chrome console, run script below
 * 3. Copy result.
 */

/**
 * IMPORT NAMESPACES
 * 1. Open http://localhost:4502/crx/explorer/nodetypes/index.jsp
 * 2. Click "Import Node Types"
 * 3. Paste CND from above
 * 4. Check the checkbox titled "Automatically register defined namespaces."
 * 5. Submit
 */

(function(){
  var namespacesCnd = "";
  document.querySelectorAll("#mainTable > tbody table > tbody > tr")
  .forEach(tr => {
    var url = tr.children[0].innerHTML.replace(" ", "").trim();
    var prefix = tr.children[1].innerHTML.replace(" ", "").trim();
    namespacesCnd += "<'" + prefix +"'='" + url +"'>\n"
  });
  console.log(namespacesCnd)
})()