檢查是否在微信瀏覽器、安卓還是iOS平臺

function check_wx() {

  //是否在微信裏
  var ua = navigator.userAgent.toLowerCase();
  var isWeixin = ua.indexOf('micromessenger') != -1;
  if (isWeixin) {
    //do something

  }

function get_pingtai() {

  if (/(iPhone|iPad|iPod|iOS)/i.test(navigator.userAgent)) {

    //蘋果端
    return 3;
  } else if (/(Android)/i.test(navigator.userAgent)) {

    //安卓端
    return 2;
  } else {

    //pc端 
    return 1;
  };


}