Added callback support in init

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## Unreleased
 
+* Add support for passing callback function to init.
 * Fix bug to check that Window localStorage is available for use.
 
 ## 2.4.0 (September 4, 2015)

README.md

@@ -134,4 +134,8 @@ The status and response from the server are passed to the callback function, whi
   };
 ```
 
+You can also pass a callback function to init, which will get called after the SDK finishes its asynchronous loading. Note: no values are passed to the init callback function:
+
+    amplitude.init("YOUR_API_KEY_HERE", "USER_ID_HERE", null, callback_function);
+
 In the case that `optOut` is true, then no event will be logged, but the callback will be called. In the case that `batchEvents` is true, if the batch requirements `eventUploadThreshold` and `eventUploadPeriodMillis` are not met when `logEvent` is called, then no request is sent, but the callback is still called. In these cases, the callback will be called with an input status of 0 and response 'No request sent'.

amplitude.js

@@ -175,7 +175,7 @@ Amplitude.prototype._newSession = false;
  *   - includeUtm (boolean) Whether to send utm parameters with events. Defaults to false.
  *   - includeReferrer (boolean) Whether to send referrer info with events. Defaults to false.
  */
-Amplitude.prototype.init = function(apiKey, opt_userId, opt_config) {
+Amplitude.prototype.init = function(apiKey, opt_userId, opt_config, callback) {
   try {
     this.options.apiKey = apiKey;
     if (opt_config) {
@@ -251,6 +251,10 @@ Amplitude.prototype.init = function(apiKey, opt_userId, opt_config) {
   } catch (e) {
     log(e);
   }
+
+  if (callback && typeof(callback) === 'function') {
+    callback();
+  }
 };
 
 Amplitude.prototype.isNewSession = function() {

src/amplitude.js

@@ -63,7 +63,7 @@ Amplitude.prototype._newSession = false;
  *   - includeUtm (boolean) Whether to send utm parameters with events. Defaults to false.
  *   - includeReferrer (boolean) Whether to send referrer info with events. Defaults to false.
  */
-Amplitude.prototype.init = function(apiKey, opt_userId, opt_config) {
+Amplitude.prototype.init = function(apiKey, opt_userId, opt_config, callback) {
   try {
     this.options.apiKey = apiKey;
     if (opt_config) {
@@ -139,6 +139,10 @@ Amplitude.prototype.init = function(apiKey, opt_userId, opt_config) {
   } catch (e) {
     log(e);
   }
+
+  if (callback && typeof(callback) === 'function') {
+    callback();
+  }
 };
 
 Amplitude.prototype.isNewSession = function() {

test/amplitude.js

@@ -60,6 +60,19 @@ describe('Amplitude', function() {
       amplitude.init(apiKey, userId, {language: 'en-GB'});
       assert.propertyVal(amplitude.options, 'language', 'en-GB');
     });
+
+    it ('should not run callback if invalid callback', function() {
+      amplitude.init(apiKey, userId, null, 'invalid callback');
+    });
+
+    it ('should run valid callbacks', function() {
+      var counter = 0;
+      var callback = function() {
+        counter++;
+      };
+      amplitude.init(apiKey, userId, null, callback);
+      assert.equal(counter, 1);
+    });
   });
 
   describe('setUserProperties', function() {