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

static/js/index.js

Index: static/js/index.js
===================================================================
new file mode 100644
--- /dev/null
+++ b/static/js/index.js
@@ -0,0 +1,77 @@
+"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"
+    },
+    "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"
+    }
+  };
+
+  function setupHeroDownloadButton()
+  {
+    var heroDownloadButton = document.getElementById("hero-download-button");
+    var detectedPlatform;
+
+    for (var key in supportedPlatforms) if (bowser[key]) detectedPlatform = key;
+
+    if (!detectedPlatform) return;
+
+    document.body.classList.add(detectedPlatform);
+
+    if (detectedPlatform === "maxthon") return;
+    
+    heroDownloadButton.href = supportedPlatforms[detectedPlatform].installer;
+    heroDownloadButton.textContent = document
+      .getElementById("hero-download-button-template")
+      .innerHTML
+      .replace("browser", supportedPlatforms[detectedPlatform].label);
+    
+    heroDownloadButton.addEventListener("click", function(event)
+    {
+      if (detectedPlatform !== "chrome") return;
+      event.preventDefault();
+      chrome.webstore.install();
+    });
+  }
+
+  if (bowser) setupHeroDownloadButton();
+
+}());