Handle dates without double-escaping

lib/json2csv.js

@@ -249,7 +249,15 @@ function createColumnContent(params, str) {
               .replace(/\u2029/g, '\r');
           }
 
-          if (typeof val === 'object') stringifiedElement = JSON.stringify(stringifiedElement);
+          if (typeof val === 'object') {
+            // In some cases (e.g. val is a Date), stringifiedElement is already a quoted string. 
+            // Strip the leading and trailing quotes if so, so we don't end up double-quoting it
+            stringifiedElement = replaceQuotationMarks(stringifiedElement, '');
+
+            // If val is a normal object, we want to escape its JSON so any commas etc
+            // don't get interpreted as field separators
+            stringifiedElement = JSON.stringify(stringifiedElement);
+          }
 
           if (params.quotes !== '"') {
             stringifiedElement = replaceQuotationMarks(stringifiedElement, params.quotes);

test/fixtures/csv/date.csv

@@ -0,0 +1,2 @@
+"date"
+"2017-01-01T00:00:00.000Z"

test/helpers/load-fixtures.js

@@ -9,6 +9,7 @@ var fixtures = [
   'withoutQuotes',
   'withNotExistField',
   'quotes',
+  'date',
   'selected',
   'reversed',
   'tsv',

test/index.js

@@ -340,6 +340,16 @@ async.parallel(loadFixtures(csvFixtures), function (err) {
     });
   });
 
+  test('should handle date', function (t) {
+    json2csv({
+      data: {'date': new Date("2017-01-01T00:00:00.000Z")}
+    }, function (error, csv) {
+      t.error(error);
+      t.equal(csv, csvFixtures.date);
+      t.end();
+    });
+  });
+
   test('should flatten embedded JSON', function (t) {
     json2csv({
       data: {'field1': {embeddedField1: 'embeddedValue1', embeddedField2: 'embeddedValue2'}},