A quickly-implemented, barely-tested JSONP client implementation, without jQuery.

jsonp.js

function getJSONP(address, callback) {
  const random = Math.floor(Math.random() * 65536)
  const callbackName = 'getJSONP_callback_' + random
  window[callbackName] = function() {
    document.body.removeChild(script)
    delete window[callbackName]
    callback.apply(null, arguments)
  }

  const script = document.createElement('script')
  script.src = address.replace('${callback}', callbackName)
  document.body.appendChild(script)
}