axios · DigitalBrainJS · Mar 18, 2021 · Mar 18, 2021 · Mar 19, 2021 · Mar 19, 2021
diff --git a/README.md b/README.md
@@ -474,10 +474,10 @@ These are the available config options for making requests. Only the `url` is re
     silentJSONParsing: true, // default value for the current Axios version
 
     // try to parse the response string as JSON even if `responseType` is not 'json'
-    forcedJSONParsing: true;
+    forcedJSONParsing: true,
 
     // throw ETIMEDOUT error instead of generic ECONNABORTED on request timeouts
-    clarifyTimeoutError: false,
+    clarifyTimeoutError: false
   }
 }
 ```

diff --git a/lib/defaults.js b/lib/defaults.js
@@ -26,6 +26,21 @@ function getDefaultAdapter() {
   return adapter;
 }
 
+function stringifySafely(rawValue, parser, encoder) {
+  if (utils.isString(rawValue)) {
+    try {
+      (parser || JSON.parse)(rawValue);
+      return utils.trim(rawValue);
+    } catch (e) {
+      if (e.name !== 'SyntaxError') {
+        throw e;
+      }
+    }
+  }
+
+  return (encoder || JSON.stringify)(rawValue);
+}
+
 var defaults = {
 
   transitional: {
@@ -56,9 +71,10 @@ var defaults = {
       setContentTypeIfUnset(headers, 'application/x-www-form-urlencoded;charset=utf-8');
       return data.toString();
     }
+
     if (utils.isObject(data) || (headers && headers['Content-Type'] === 'application/json')) {
       setContentTypeIfUnset(headers, 'application/json');
-      return JSON.stringify(data);
+      return stringifySafely(data);
     }
     return data;
   }],

diff --git a/test/specs/transform.spec.js b/test/specs/transform.spec.js
@@ -174,4 +174,31 @@ describe('transform', function () {
       done();
     });
   });
+
+  it('should not stringify twice if the payload was already encoded to the JSON string', function (done) {
+    var response;
+    var rawPayload = '{"x": 123}';
+
+    axios.post('/foo', rawPayload, {
+      responseType: 'text',
+      headers: {'Content-Type': 'application/json'}
+    }).then(function (_response) {
+      response = _response;
+    }, function (err) {
+      done(err);
+    });
+
+    getAjaxRequest().then(function (request) {
+      request.respondWith({
+        status: 200,
+        responseText: request.body
+      });
+
+      setTimeout(function () {
+        expect(response).toBeTruthy();
+        expect(request.params).toEqual(rawPayload);
+        done();
+      }, 100);
+    });
+  });
 });