Feature detection to avoid errors

stopsatgreen · Jul 5, 2013 · 136446b · 136446b
1 parent 24f6b3f
commit 136446b
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Showing 3 changed files with 8 additions and 5 deletions.
diff --git a/Code Examples/Chapter 06/battery-event.html b/Code Examples/Chapter 06/battery-event.html
@@ -18,9 +18,10 @@ <h2 id="status"></h2>
 	var status,
 			el = document.getElementById('status'),
       meter = document.querySelector('meter'),
-			battery = navigator.battery || navigator.mozBattery || navigator.webkitBattery,
+			battery = navigator.battery || navigator.mozBattery || navigator.webkitBattery;
+	if (!battery) { return false; }
 // Get charge level and update meter
-			chargeLevel = function () {
+	var	chargeLevel = function () {
 				meter.value = battery.level;
 				meter.textContent = battery.level;
 			},

diff --git a/Code Examples/Chapter 06/battery.html b/Code Examples/Chapter 06/battery.html
@@ -17,9 +17,10 @@ <h2 id="status"></h2>
   'use strict';
 	var el = document.getElementById('status'),
       meter = document.querySelector('meter'),
-			battery = navigator.battery || navigator.webkitBattery,
+			battery = navigator.battery || navigator.mozBattery || navigator.webkitBattery;
+  if (!battery) { return false; }
 // Check charge status and update h2
-      status = (battery.charging) ? 'Charging' : 'Discharging';
+  var status = (battery.charging) ? 'Charging' : 'Discharging';
   el.textContent = status;
 // Get charge level and update meter
   meter.value = battery.level;

diff --git a/Code Examples/Chapter 06/network.html b/Code Examples/Chapter 06/network.html
@@ -12,11 +12,12 @@ <h1>Getting Connection...</h1>
 <script>
 document.addEventListener('DOMContentLoaded',function () {
 	'use strict';
-	navigator.connection = (
+	var hasConnect = navigator.connection = (
 		navigator.connection ||
 		navigator.mozConnection ||
 		navigator.webkitConnection
 	);
+	if (!hasConnect) { return false; }
 	var status,
 			target = document.querySelector('h1'),
 			showStatus = function () {