window.onload = function () {
  // if(this.sessionStorage.getItem("preloading")) return
  let pre = document.getElementById('pre')
  if (!pre) {
    let pre = document.createElement("div")
    pre.setAttribute('id', 'pre')
    pre.setAttribute('style', 'position: fixed; top: 0; left: 0; right: 0; bottom: 0; z-index: 100000; ')
    let cover = document.createElement('div')
    cover.setAttribute('style', 'background-color: rgba(0, 0, 0, .8); width: 100%; height: 100%;')
    let loading = document.createElement('div')
    loading.setAttribute('style', 'position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%);')
    let icon = document.createElement('div')
    icon.setAttribute('class','line-scale');
    for (let i = 0; i < 5; i++) {
      let div = document.createElement('div');
      icon.appendChild(div);
    }
    loading.appendChild(icon)
    cover.appendChild(loading)
    pre.appendChild(cover)
    document.body.appendChild(pre)
    let preCss = document.createElement("link");
    preCss.setAttribute("href","/preloading.css");
    preCss.setAttribute("rel","stylesheet");
    preCss.setAttribute("type","text/css");
    let head = document.getElementsByTagName("head");
    head[0].appendChild(preCss);
  }
  let chunk = document.createElement("script")
  chunk.setAttribute("src", "/js/chunk-vendors.3c13fdca.js") // 同步
  document.body.appendChild(chunk)
  let app = document.createElement("script")
  app.setAttribute("src", "/js/app.75c8728b.js") // 同步
  document.body.appendChild(app)

}