微信打开APP更新页面开发注意点

$(function () {
  var r = document.body.offsetWidth / 800;
  $(".bg").css("transform-origin", "0 0 0").css("transform", "scale(" + r + ")");

  if (!is_weixn()) {
    $(".top_div").css("display", "none");
  }
});
$(window).resize(function () {
  var r = document.body.offsetWidth / 800;
  $(".bg").css("transform-origin", "0 0 0").css("transform", "scale(" + r + ")");
});

function is_weixn() {
  var ua = navigator.userAgent.toLowerCase();
  if (ua.match(/MicroMessenger/i) == "micromessenger") {
    return true;
  } else {
    return false;
  }
}

let fileurl = "https://www.psvmc.cn/123.apk";
var isSupportDownload = 'download' in document.createElement('a');
if (isSupportDownload) {
  var $a = $("<a>");
  $a.attr({
    href: fileurl,
    download: 'filename'
  }).hide().appendTo($("body"))[0].click();
} else {
  window.open(fileurl)
}