如何动态引入js

try {
  await loadJs('https://xxxxxx.js')
  console.log(' 加载成功 ')
} catch {
  console.log(' 加载失败 ')
}

function loadJs(path) {
  if (document.head.querySelector(`script[src="${path}"]`) != null) return

  var script = document.createElement('script')
  script.src = path
  script.type = 'text/javascript'
  document.head.appendChild(script)

  return new Promise((res, rej) => {
    script.addEventListener('load', res)
    script.addEventListener('error', rej)
  })
}