Merge pull request #5 from flatiron/toJSON

Error.prototype.toJSON

lib/errs.js

@@ -14,6 +14,23 @@ var events = require('events'),
 //
 exports.registered = {};
 
+//
+// Add `Error.prototype.toJSON` if it doesn't exist.
+//
+if (!Error.prototype.toJSON) {
+  Object.defineProperty(Error.prototype, 'toJSON', {
+    enumerable: false,
+    value: function () {
+      return mixin({
+        message: this.message,
+        stack: this.stack,
+        arguments: this.arguments,
+        type: this.type
+      }, this);
+    }
+  });
+}
+
 //
 // ### function create (type, opts)
 // #### @type {string} **Optional** Registered error type to create
@@ -173,7 +190,7 @@ exports.handle = function (error, callback, stream) {
   if (typeof callback === 'function') {
     callback(error);
   }
-  
+
   if (typeof callback !== 'function' || stream) {
     var emitter = stream || callback || new events.EventEmitter();
     process.nextTick(function () { emitter.emit('error', error); });
@@ -207,3 +224,38 @@ exports.register = function (type, proto) {
 exports.unregister = function (type) {
   delete exports.registered[type];
 };
+
+//
+// ### function mixin (target [source0, source1, ...])
+// Copies enumerable properties from `source0 ... sourceN`
+// onto `target` and returns the resulting object.
+//
+function mixin(target) {
+  //
+  // Quickly and performantly (in V8) `Arrayify` arguments.
+  //
+  var len = arguments.length,
+      args = new Array(len - 1),
+      i = 1;
+
+  for (; i < len; i++) {
+    args[i - 1] = arguments[i];
+  }
+
+  args.forEach(function (o) {
+    Object.keys(o).forEach(function (attr) {
+      var getter = o.__lookupGetter__(attr),
+          setter = o.__lookupSetter__(attr);
+
+      if (!getter && !setter) {
+        target[attr] = o[attr];
+      }
+      else {
+        if (setter) { target.__defineSetter__(attr, setter) }
+        if (getter) { target.__defineGetter__(attr, getter) }
+      }
+    });
+  });
+
+  return target;
+}

test/errs-test.js

@@ -146,4 +146,18 @@ vows.describe('errs').addBatch({
       }
     }
   }
+}).addBatch({
+  "Using errs module": {
+    "Error.prototype.toJSON": {
+      "should exist": function () {
+        assert.isFunction(Error.prototype.toJSON);
+
+        var json = (new Error('Testing 12345')).toJSON();
+
+        ['message', 'stack', 'arguments', 'type'].forEach(function (prop) {
+          assert.isObject(Object.getOwnPropertyDescriptor(json, prop));
+        })
+      }
+    }
+  }
 }).export(module);