prototype: Make String#isJSON return false for empty or blank strings. Make Ajax.Response#responseJSON null when Ajax.Response#responseText is empty or blank.

CHANGELOG

@@ -1,3 +1,5 @@
+* Make String#isJSON return false for empty or blank strings. Make Ajax.Response#responseJSON null when Ajax.Response#responseText is empty or blank. [Andrew Dupont, Thomas Fuchs, Tobie Langel]
+
 * Make Ajax.Response#_getResponseJSON use Ajax.Response#responseText. [Tobie Langel]
 
 * Remove the forked declaration of Hash#_each. As we are now systematically cloning the object upon instantiation, preventing iteration of shadowed properties is no longer required. [Tobie Langel]

src/ajax.js

@@ -288,8 +288,9 @@ Ajax.Response = Class.create({
   _getResponseJSON: function() {
     var options = this.request.options;
     if (!options.evalJSON || (options.evalJSON != 'force' && 
-      !(this.getHeader('Content-type') || '').include('application/json')))
-        return null;
+      !(this.getHeader('Content-type') || '').include('application/json')) || 
+        this.responseText.blank())
+          return null;
     try {
       return this.responseText.evalJSON(options.sanitizeJSON);
     } catch (e) {

src/string.js

@@ -166,7 +166,9 @@ Object.extend(String.prototype, {
   },
 
   isJSON: function() {
-    var str = this.replace(/\\./g, '@').replace(/"[^"\\\n\r]*"/g, '');
+    var str = this;
+    if (str.blank()) return false;
+    str = this.replace(/\\./g, '@').replace(/"[^"\\\n\r]*"/g, '');
     return (/^[,:{}\[\]0-9.\-+Eaeflnr-u \n\r\t]*$/).test(str);
   },
   

test/unit/ajax.html

@@ -312,7 +312,15 @@
           parameters: Fixtures.json,
           onComplete: function(transport) { assertEqual(123, transport.responseJSON.test) }
         }));
-      
+        
+        new Ajax.Request("/response", extendDefault({
+          parameters: {
+            'Content-Length': 0,
+            'Content-Type': 'application/json'
+          },
+          onComplete: function(transport) { assertNull(transport.responseJSON) }
+        }));
+        
         new Ajax.Request("/response", extendDefault({
           evalJSON: false,
           parameters: Fixtures.json,

test/unit/string.html

@@ -504,7 +504,9 @@
     }},
     
     testIsJSON: function() {with(this) {
-      assert(''.isJSON());
+      assert(!''.isJSON());
+      assert(!'     '.isJSON());
+      assert('""'.isJSON());
       assert('"foo"'.isJSON());
       assert('{}'.isJSON());
       assert('[]'.isJSON());
@@ -517,13 +519,13 @@
       assert(!'new'.isJSON());
       assert(!'\u0028\u0029'.isJSON());
       // we use '@' as a placeholder for characters authorized only inside brackets,
-      // so this tests make sure it is considered as authorized.
+      // so this tests make sure it is not considered authorized elsewhere.
       assert(!'@'.isJSON());
     }},
 
     testEvalJSON: function() {with(this) {
-      var valid = '{test: \n\r"hello world!"}';
-      var invalid = '{test: "hello world!"';
+      var valid = '{"test": \n\r"hello world!"}';
+      var invalid = '{"test": "hello world!"';
       var dangerous = '{});attackTarget = "attack succeeded!";({}';
 
       // use smaller huge string size for KHTML
@@ -552,6 +554,16 @@
       Prototype.JSONFilter = temp;
       
       assertMatch(123, huge.evalJSON(true).last().test);
+      
+      assertEqual('', '""'.evalJSON());
+      assertEqual('foo', '"foo"'.evalJSON());
+      assert('object', typeof '{}'.evalJSON());
+      assert(Object.isArray('[]'.evalJSON()));
+      assertNull('null'.evalJSON());
+      assert(123, '123'.evalJSON());
+      assertIdentical(true, 'true'.evalJSON());
+      assertIdentical(false, 'false'.evalJSON());
+      assertEqual('"', '"\\""'.evalJSON());
     }}
   }, 'testlog');
 // ]]>