var load = require('scriptloader')
load('//my-widget.js') // load js from current domain
load('//remote.com/their-widget.js') // load js from remote domain

// returns the script. you can listen for load/error on this directly
load('//cdnjs.cloudflare.com/ajax/libs/json3/3.2.4/json3.min.js').addEventListener('load', function() {
  console.log('it is loaded')
})

// or just supply a callback
load('//cdnjs.cloudflare.com/ajax/libs/json3/3.2.5/json3.min.js', function(err, script) {
  console.log('it is loaded')
})

// you can also specify a target document where you want the script to be loaded
load(iframe.contentWindow.document, '//cdnjs.cloudflare.com/ajax/libs/json3/3.2.5/json3.min.js', function(err, script) {
  console.log('it is loaded')
})