Embed custom scripts by Bookmarklet

bookmarklet.js

(function (_) {
  var $ = document.createElement('SCRIPT')
  $.src = _
  $.onerror = function () { alert('Failed to load ' + _) }
  document.body.appendChild($)
} ("data:application/javascript,alert('Hello, world.')"))

bookmarklet.md

[Add Alert Bookmarklet](javascript:(function (_) {var $ = document.createElement('SCRIPT'); $.src = _; $.onerror = function () { alert('Failed to load ' + _) }; document.body.appendChild($)} ('data:application/javascript,alert('Hello, world.')')))

Add Alert Bookmarklet