app_store.js

var is_android = navigator.userAgent.toLowerCase().indexOf('android') !== -1;
var is_ios = /iphone|ipad|ipod/i.test( navigator.userAgent);
var link;
var links = {
  android : 'https://play.google.com/store?hl=zh-TW',
  ios: 'https://itunes.apple.com/tw/genre/ios/id36?mt=8',
  default: 'http://google.com'
};


if( is_android ){
  link = links.android;
}
else if( is_ios ){
  link = links.ios;
}
else{
  link = links.default;
}

window.open(link);