Don’t set a default Content-Type on an Ajax.Request if the user specifies a falsy contentType option. (Closes prototypejs#313)

Author: savetheclocktower

src/prototype/ajax/request.js

@@ -236,8 +236,12 @@ Ajax.Request = Class.create(Ajax.Base, {
     };
 
     if (this.method == 'post') {
-      headers['Content-type'] = this.options.contentType +
-        (this.options.encoding ? '; charset=' + this.options.encoding : '');
+      // Don't set the `Content-Type` header if the user has explicitly set
+      // `contentType` to anything falsy.
+      if (this.options.contentType) {
+        headers['Content-type'] = this.options.contentType +
+          (this.options.encoding ? '; charset=' + this.options.encoding : '');
+      }
 
       /* Force "Connection: close" for older Mozilla browsers to work
        * around a bug where XMLHttpRequest sends an incorrect

test/unit/tests/ajax.test.js

@@ -495,5 +495,17 @@ suite("Ajax", function () {
     Ajax.Request.prototype.isSameOrigin = isSameOrigin;
   });
 
+  test('can omit content-type', function () {
+    new Ajax.Request('/inspect', extendDefault({
+      method: 'post',
+      contentType: false,
+      onSuccess: function (response) {
+        // If we omit Content-Type, the browser will provide its own.
+        var contentType = response.responseJSON.headers['content-type'];
+        assert(contentType.indexOf('text/plain') > -1);
+      }
+    }));
+  });
+
 });