Add debugInfo method

backbone.js

@@ -2133,5 +2133,33 @@
     };
   };
 
+  // Provide useful information when things go wrong.
+  Backbone.debugInfo = function() {
+    // Use the `partialRight` function as a Lodash indicator. It was never in
+    // Underscore, has been in Lodash at least since version 1.3.1, and is
+    // unlikely to be mixed into Underscore since nobody needs it.
+    var lodash = !!_.partialRight;
+    var info = {
+      backbone: Backbone.VERSION,
+      // Is this the exact released version, or a later development version?
+      /* This is automatically temporarily replaced when publishing a release,
+         so please don't edit this. */
+      distribution: 'MARK_DEVELOPMENT',
+      _: (lodash ? 'lodash ' : '') + _.VERSION,
+      $: !$ ? false : $.fn && $.fn.jquery ? $.fn.jquery :
+        $.zepto ? 'zepto' : $.ender ? 'ender' : true
+    };
+    if (typeof root.Deno !== 'undefined') {
+      info.deno = _.pick(root.Deno, 'version', 'build');
+    } else if (typeof root.process !== 'undefined') {
+      info.process = _.pick(root.process, 'version', 'platform', 'arch');
+    } else if (typeof root.navigator !== 'undefined') {
+      info.navigator = _.pick(root.navigator, 'userAgent', 'platform', 'webdriver');
+    }
+    /* eslint-disable-next-line no-console */
+    console.debug('Backbone debug info: ', JSON.stringify(info, null, 4));
+    return info;
+  };
+
   return Backbone;
 });

package.json

@@ -25,6 +25,7 @@
     "karma-qunit": "^4.1.2",
     "phantomjs-prebuilt": "^2.1.7",
     "qunit": "^2.17.2",
+    "replace-in-file": "^7.0.1",
     "uglify-js": "^3.14.5"
   },
   "scripts": {
@@ -33,7 +34,9 @@
     "alias-sourcemap": "cpy --rename=backbone-min.map backbone-min.js.map .",
     "doc": "docco backbone.js && docco examples/todos/todos.js examples/backbone.localStorage.js",
     "lint": "eslint backbone.js test/*.js",
-    "prepublishOnly": "npm run test && npm run build && npm run alias-sourcemap && npm run doc"
+    "mark-release": "replace-in-file MARK_DEVELOPMENT MARK_RELEASE backbone.js",
+    "mark-develop": "replace-in-file MARK_RELEASE MARK_DEVELOPMENT backbone.js",
+    "prepublishOnly": "npm run test && npm run mark-release && npm run build && npm run alias-sourcemap && npm run doc && git add -u && npm run mark-develop"
   },
   "main": "backbone.js",
   "version": "1.4.1",

test/debuginfo.js

@@ -0,0 +1,43 @@
+/* eslint-disable no-console */
+
+(function(QUnit) {
+
+  var logs, originalDebug = console.debug;
+
+  function spyDebug() {
+    logs.push(arguments);
+    originalDebug.apply(console, arguments);
+  }
+
+  QUnit.module('Backbone.debugInfo', {
+
+    beforeEach: function() {
+      logs = [];
+      console.debug = spyDebug;
+    },
+
+    afterEach: function() {
+      console.debug = originalDebug;
+      logs = undefined;
+    }
+  });
+
+  QUnit.test('debugInfo', function(assert) {
+    var info = Backbone.debugInfo();
+    assert.strictEqual(info.backbone, Backbone.VERSION, 'includes Backbone version');
+    assert.strictEqual(info.distribution, 'MARK_DEVELOPMENT', 'distribution mark sticks to development');
+    assert.strictEqual(info._, _.VERSION, 'includes Underscore version');
+    assert.strictEqual(info.$, $.fn.jquery, 'includes jQuery version');
+    if (typeof navigator !== 'undefined') {
+      assert.ok(typeof info.navigator === 'object');
+      assert.strictEqual(info.navigator.userAgent, navigator.userAgent, 'includes user agent');
+      assert.strictEqual(info.navigator.platform, navigator.platform, 'includes navigator platform');
+      assert.strictEqual(info.navigator.webdriver, navigator.webdriver, 'includes webdriver state');
+    }
+    assert.strictEqual(logs.length, 1, 'prints to console as side effect');
+    var debugArgs = logs[0];
+    var infoString = JSON.stringify(info, null, 4);
+    assert.strictEqual(debugArgs[1], infoString, 'prints payload as second argument');
+  });
+
+})(QUnit);

test/index.html

@@ -14,6 +14,7 @@
   <script src="setup/dom-setup.js"></script>
   <script src="setup/environment.js"></script>
   <script src="noconflict.js"></script>
+  <script src="debuginfo.js"></script>
   <script src="events.js"></script>
   <script src="model.js"></script>
   <script src="collection.js"></script>