添加js文件和删除js

onloadJS: function (url, callback) {
  let script = document.createElement('script')
  script.src = url
  script.type = 'text/javascript'
  document.getElementsByTagName('head')[0].appendChild(script)
  script.onload = callback
},
removeJS: function (url) {
  let scripts = document.getElementsByTagName('script')
  for (let bb of scripts) {
    if (bb.src.indexOf(url) > -1) {
      document.getElementsByTagName('head')[0].removeChild(bb)
    }
  }
}