js判断url是否可用

问题

需要判断url是否可用，再去执行其他操作，代码如下：

const loadScript = (url) => {
  return new Promise((resolve, reject) => {
    const script = document.createElement('script')
    script.onload = () => resolve(true)
    script.onerror = () => resolve(false)
    script.src = url
    const head = document.head || document.getElementsByTagName('head')[0];
    (document.body || head).appendChild(script)
  })
}

const checkUrl = async() => {
  const url = 'xxxx';
  const flag = await loadScript(url)
  if (flag) {
    // do something...
  }
}