Fixes #35 - Progressively enhance install button with appropriate links and text

static/js/index.js

 "use strict";
 
 (function()
 {
   var supportedPlatforms = {
+
     // Desktop browsers
-    "chrome": {
-      installer: "https://chrome.google.com/webstore/detail/cfhdojbkjhnklbpkdaibdccddilifddb",
-      label: "Chrome"
-    },
-    "opera": {
-      installer: "https://addons.opera.com/extensions/details/opera-adblock/?display=en-US",
-      label: "Opera"
-    },
-    "yandexbrowser": {
-      installer: "https://chrome.google.com/webstore/detail/cfhdojbkjhnklbpkdaibdccddilifddb",
-      label: "Yandex Browser"
-    },
-    "msie": {
-      installer: "https://update.adblockplus.org/latest/adblockplusie.exe",
-      label: "Internet Explorer"
-    },
-    "msedge": {
-      installer: "https://www.microsoft.com/store/p/adblock-plus/9nblggh4r9nz",
-      label: "Micrsoft Edge"
-    },
-    "firefox": {
-      installer: "https://update.adblockplus.org/latest/adblockplusfirefox.xpi",
-      label: "Firefox"
-    },
-    "safari": {
-      installer: "https://update.adblockplus.org/latest/adblockplussafari.safariextz",
-      label: "Safari"
-    },
+    "chrome": "https://chrome.google.com/webstore/detail/cfhdojbkjhnklbpkdaibdccddilifddb",
+    "opera": "https://addons.opera.com/extensions/details/opera-adblock/?display=en-US",
+    "yandexbrowser": "https://chrome.google.com/webstore/detail/cfhdojbkjhnklbpkdaibdccddilifddb",
+    "msie": "https://update.adblockplus.org/latest/adblockplusie.exe",
+    "msedge": "https://www.microsoft.com/store/p/adblock-plus/9nblggh4r9nz",
+    "firefox": "https://update.adblockplus.org/latest/adblockplusfirefox.xpi",
+    "safari": "https://update.adblockplus.org/latest/adblockplussafari.safariextz",
     "maxthon": "",
 
     // Mobile platforms
-    "ios": {
-      installer: "https://eyeo.to/adblockbrowser/ios/abp-website",
-      label: "iOS",
-    },
-    "android": {
-      installer: "https://eyeo.to/adblockbrowser/android/abp-website",
-      label: "Android"
-    }
+    "ios": "https://eyeo.to/adblockbrowser/ios/abp-website",
+    "android": "https://eyeo.to/adblockbrowser/android/abp-website"
   };
 
   function setupHeroDownloadButton()
   {
-    var heroDownloadButton = document.getElementById("hero-download-button");
-    var detectedPlatform;
-
-    for (var key in supportedPlatforms) if (bowser[key]) detectedPlatform = key;
+    var detectedPlatform = Object.keys(supportedPlatforms)
+      .find(bowser.hasOwnProperty.bind(bowser));
 
     if (!detectedPlatform) return;
 
     document.body.classList.add(detectedPlatform);
 
-    if (detectedPlatform === "maxthon") return;
-    
-    heroDownloadButton.href = supportedPlatforms[detectedPlatform].installer;
+    if (detectedPlatform == "maxthon") return;
+
+    var heroDownloadButton = document.getElementById("hero-download-button");
+    heroDownloadButton.href = supportedPlatforms[detectedPlatform];
     heroDownloadButton.textContent = document
-      .getElementById("hero-download-button-template")
-      .innerHTML
-      .replace("browser", supportedPlatforms[detectedPlatform].label);
+      .getElementById("download-label-" + detectedPlatform)
+      .textContent;
     
     heroDownloadButton.addEventListener("click", function(event)
     {
-      if (detectedPlatform !== "chrome") return;
+      if (typeof chrome == "undefined") return;
       event.preventDefault();
-      chrome.webstore.install();
+
+      try
+      {
+        chrome.webstore.install();
+      }
+      catch(error)
+      {
+        window.location = "/" + this.hreflang + "/download";
+      }
     });
   }
 
-  if (bowser) setupHeroDownloadButton();
+  if (typeof bowser != "undefined") setupHeroDownloadButton();
 
 }());