Extended cache bust to custom checks

README.md

@@ -116,6 +116,13 @@ Offline.options = {checks: {image: {url: 'my-image.gif'}, active: 'image'}}
 The one cavet is that with the image method, we can't distinguish a 404 from a genuine connection issue, so any error at all will
 appear to Offline as a connection issue.
 
+By default, Offline will add a 'cacheBust' parameter to the xhr or image URL to prevent the browser from caching the request.
+You can disable this by setting the value to false:
+
+```javascript
+Offline.options = {checks: {xhr: {url: '/connection-test'}, cacheBust:false}};
+```
+
 Offline also includes a check called `'up'` and another called `'down'` which will always report being up or down respectively for
 testing.  You can activate them by setting the `active` option, adding a data attribute to your script tag with the name
 `data-simulate` and value `'up'` or `'down'`, or by setting `localStorage.OFFLINE_SIMULATE` to `'up'` or `'down'`.

coffee/offline.coffee

@@ -20,16 +20,18 @@ defaultOptions =
     xhr:
       url: ->
         # This can be any endpoint, even one that will 404.
-        "/favicon.ico?_=#{ (new Date()).getTime() }"
+        "/favicon.ico"
       timeout: 5000
       type: 'HEAD'
     image:
       url: ->
         # This can be any image, this is the better option if your image is on a different domain, otherwise just use XHR
-        "/favicon.ico?_=#{ (new Date()).getTime() }"
+        "/favicon.ico"
 
     active: 'xhr'
 
+    cacheBust: true
+
   checkOnLoad: false
 
   interceptRequests: true
@@ -38,6 +40,7 @@ defaultOptions =
 
   deDupBody: false
 
+
 grab = (obj, key) ->
   cur = obj
   parts = key.split('.')
@@ -156,6 +159,16 @@ checkXHR = (xhr, onUp, onDown) ->
 
       _onreadystatechange?(arguments...)
 
+getURL = (url) ->
+  if Offline.getOption('checks.cacheBust')
+    bust = 'cacheBust' + '=' + (new Date).getTime()
+    if url.indexOf('?') > -1
+      bust = '&' + bust
+    else
+      bust = '?' + bust
+    url = url + bust
+  url
+
 Offline.checks = {}
 Offline.checks.xhr = ->
   xhr = new XMLHttpRequest
@@ -164,7 +177,8 @@ Offline.checks.xhr = ->
 
   # It doesn't matter what this hits, even a 404 is considered up.  It is important however that
   # it's on the same domain and port, so CORS issues don't come into play.
-  xhr.open(Offline.getOption('checks.xhr.type'), Offline.getOption('checks.xhr.url'), true)
+
+  xhr.open(Offline.getOption('checks.xhr.type'), getURL(Offline.getOption('checks.xhr.url')), true)
 
   if xhr.timeout?
     xhr.timeout = Offline.getOption('checks.xhr.timeout')
@@ -183,7 +197,7 @@ Offline.checks.image = ->
   img = document.createElement 'img'
   img.onerror = Offline.markDown
   img.onload = Offline.markUp
-  img.src = Offline.getOption('checks.image.url')
+  img.src = getURL(Offline.getOption('checks.image.url'))
 
   undefined
 

js/offline.js

@@ -1,5 +1,5 @@
 (function() {
-  var Offline, checkXHR, defaultOptions, extendNative, grab, handlers, init;
+  var Offline, checkXHR, defaultOptions, extendNative, getURL, grab, handlers, init;
 
   extendNative = function(to, from) {
     var e, key, results, val;
@@ -29,17 +29,18 @@
     checks: {
       xhr: {
         url: function() {
-          return "/favicon.ico?_=" + ((new Date()).getTime());
+          return "/favicon.ico";
         },
         timeout: 5000,
         type: 'HEAD'
       },
       image: {
         url: function() {
-          return "/favicon.ico?_=" + ((new Date()).getTime());
+          return "/favicon.ico";
         }
       },
-      active: 'xhr'
+      active: 'xhr',
+      cacheBust: true
     },
     checkOnLoad: false,
     interceptRequests: true,
@@ -200,13 +201,27 @@
     }
   };
 
+  getURL = function(url) {
+    var bust;
+    if (Offline.getOption('checks.cacheBust')) {
+      bust = 'cacheBust' + '=' + (new Date).getTime();
+      if (url.indexOf('?') > -1) {
+        bust = '&' + bust;
+      } else {
+        bust = '?' + bust;
+      }
+      url = url + bust;
+    }
+    return url;
+  };
+
   Offline.checks = {};
 
   Offline.checks.xhr = function() {
     var e, xhr;
     xhr = new XMLHttpRequest;
     xhr.offline = false;
-    xhr.open(Offline.getOption('checks.xhr.type'), Offline.getOption('checks.xhr.url'), true);
+    xhr.open(Offline.getOption('checks.xhr.type'), getURL(Offline.getOption('checks.xhr.url')), true);
     if (xhr.timeout != null) {
       xhr.timeout = Offline.getOption('checks.xhr.timeout');
     }
@@ -225,7 +240,7 @@
     img = document.createElement('img');
     img.onerror = Offline.markDown;
     img.onload = Offline.markUp;
-    img.src = Offline.getOption('checks.image.url');
+    img.src = getURL(Offline.getOption('checks.image.url'));
     return void 0;
   };
 

offline.js

@@ -1,6 +1,6 @@
 /*! offline-js 0.7.14 */
 (function() {
-  var Offline, checkXHR, defaultOptions, extendNative, grab, handlers, init;
+  var Offline, checkXHR, defaultOptions, extendNative, getURL, grab, handlers, init;
   extendNative = function(to, from) {
     var e, key, results, val;
     results = [];
@@ -14,17 +14,18 @@
     checks:{
       xhr:{
         url:function() {
-          return "/favicon.ico?_=" + new Date().getTime();
+          return "/favicon.ico";
         },
         timeout:5e3,
         type:"HEAD"
       },
       image:{
         url:function() {
-          return "/favicon.ico?_=" + new Date().getTime();
+          return "/favicon.ico";
         }
       },
-      active:"xhr"
+      active:"xhr",
+      cacheBust:!0
     },
     checkOnLoad:!1,
     interceptRequests:!0,
@@ -86,9 +87,13 @@
     }) :(_onreadystatechange = xhr.onreadystatechange, xhr.onreadystatechange = function() {
       return 4 === xhr.readyState ? checkStatus() :0 === xhr.readyState && onDown(), "function" == typeof _onreadystatechange ? _onreadystatechange.apply(null, arguments) :void 0;
     });
+  }, getURL = function(url) {
+    var bust;
+    return Offline.getOption("checks.cacheBust") && (bust = "cacheBust=" + new Date().getTime(), 
+    bust = url.indexOf("?") > -1 ? "&" + bust :"?" + bust, url += bust), url;
   }, Offline.checks = {}, Offline.checks.xhr = function() {
     var e, xhr;
-    xhr = new XMLHttpRequest(), xhr.offline = !1, xhr.open(Offline.getOption("checks.xhr.type"), Offline.getOption("checks.xhr.url"), !0), 
+    xhr = new XMLHttpRequest(), xhr.offline = !1, xhr.open(Offline.getOption("checks.xhr.type"), getURL(Offline.getOption("checks.xhr.url")), !0), 
     null != xhr.timeout && (xhr.timeout = Offline.getOption("checks.xhr.timeout")), 
     checkXHR(xhr, Offline.markUp, Offline.markDown);
     try {
@@ -100,7 +105,7 @@
   }, Offline.checks.image = function() {
     var img;
     return img = document.createElement("img"), img.onerror = Offline.markDown, img.onload = Offline.markUp, 
-    void (img.src = Offline.getOption("checks.image.url"));
+    void (img.src = getURL(Offline.getOption("checks.image.url")));
   }, Offline.checks.down = Offline.markDown, Offline.checks.up = Offline.markUp, Offline.check = function() {
     return Offline.trigger("checking"), Offline.checks[Offline.getOption("checks.active")]();
   }, Offline.confirmUp = Offline.confirmDown = Offline.check, Offline.onXHR = function(cb) {