JsonpCrossDomain

/**
 * @param {string} url
 */
const jsonp = url =>
  new Promise((resolve, reject) => {
    // 创建标签
    const script = document.createElement('script')
    // 设置回调名
    const callbackId = `jsonp_${Date.now()}`
    // 拼接请求的url，异步请求在这里，判断是否已经有参数
    script.src = url.includes('?')
      ? `${url}&callback=${callbackId}`
      : `${url}?callback=${callbackId}`
    // 不发referer请求头，防止验证referer
    script.referrerPolicy = 'no-referrer'
    // 设置读取返回结果的回调函数, 必须设置在window上
    window[callbackId] = result => {
      // 释放内存
      delete window[callbackId]
      document.body.removeChild(script)
      // 结果
      result ? resolve(result) : reject('404')
    }
    script.addEventListener('error', () => reject('script create fail'))
    // 发出请求
    document.body.appendChild(script)
  })

jsonp('http://localhost:3005/jsonp?name=saber2pr&age=21').then(console.log)