Fix #12751. Ensure parseJson throws in the same situations as JSON.parse. Close gh-993.

AUTHORS.txt

@@ -134,3 +134,4 @@ Nikita Govorov <nikita.govorov@gmail.com>
 Michael Pennisi <mike@mikepennisi.com>
 Markus Staab <markus.staab@redaxo.de>
 Daniel Gálvez <dgalvez@editablething.com>
+James Huston <james@jameshuston.net>
\ No newline at end of file

src/core.js

@@ -488,18 +488,21 @@ jQuery.extend({
 	},
 
 	parseJSON: function( data ) {
-		if ( !data || typeof data !== "string") {
-			return null;
-		}
-
-		// Make sure leading/trailing whitespace is removed (IE can't handle it)
-		data = jQuery.trim( data );
-
 		// Attempt to parse using the native JSON parser first
 		if ( window.JSON && window.JSON.parse ) {
 			return window.JSON.parse( data );
 		}
 
+		if ( data === null ) {
+			return data;
+		}
+
+		if ( typeof data === "string" ) {
+			
+			// Make sure leading/trailing whitespace is removed (IE can't handle it)
+			data = jQuery.trim( data );
+
+			if ( data ) {
 				// Make sure the incoming data is actual JSON
 				// Logic borrowed from http://json.org/json2.js
 				if ( rvalidchars.test( data.replace( rvalidescape, "@" )
@@ -507,8 +510,10 @@ jQuery.extend({
 					.replace( rvalidbraces, "")) ) {
 
 					return ( new Function( "return " + data ) )();
-
 				}
+			}
+		}
+
 		jQuery.error( "Invalid JSON: " + data );
 	},
 

test/unit/ajax.js

@@ -2759,4 +2759,18 @@ if ( jQuery.ajax && ( !isLocal || hasPHP ) ) {
 			start();
 		});
 	});
+	
+	test( "jQuery.ajax - empty json gets to error callback instead of success callback.", function() {
+		expect( 1 );
+
+		stop();
+
+		jQuery.ajax( url("data/echoData.php"), {
+			error: function( _, __, error ) {
+				equal( typeof error === "object", true,  "Didn't get back error object for empty json response" );
+				start();
+			},
+			dataType: "json"
+		});
+	});
 }

test/unit/core.js

@@ -1150,9 +1150,13 @@ test("jQuery.parseHTML", function() {
 test("jQuery.parseJSON", function(){
 	expect(8);
 
-	equal( jQuery.parseJSON(), null, "Nothing in, null out." );
-	equal( jQuery.parseJSON( null ), null, "Nothing in, null out." );
-	equal( jQuery.parseJSON( "" ), null, "Nothing in, null out." );
+	raises(function() {
+		jQuery.parseJSON();
+	}, null, "parseJson now matches JSON.parse for empty input." );
+	equal(jQuery.parseJSON( null ), null, "parseJson now matches JSON.parse on null input." );
+	raises( function() {
+		jQuery.parseJSON( "" );
+	}, null, "parseJson now matches JSON.parse for empty strings." );
 
 	deepEqual( jQuery.parseJSON("{}"), {}, "Plain object parsing." );
 	deepEqual( jQuery.parseJSON("{\"test\":1}"), {"test":1}, "Plain object parsing." );
@@ -1346,3 +1350,50 @@ test("jQuery.camelCase()", function() {
 		equal( jQuery.camelCase( key ), val, "Converts: " + key + " => " + val );
 	});
 });
+
+test( "JQuery.parseJSON() test internal parseJson (using fallback) to make sure that it throws like JSON.parse", function() {
+	expect( 10 );
+
+	var jsonParse = window.JSON;
+	window.JSON = null;
+
+	raises(function() {
+		jsonParse.parse("''");
+	});
+
+	raises(function() {
+		jQuery.parseJSON("''");
+	});
+
+	raises(function() {
+		jsonParse.parse("");
+	});
+
+	raises(function() {
+		jQuery.parseJSON("");
+	});
+
+	raises(function() {
+		jsonParse.parse({});
+	});
+
+	raises(function() {
+		jQuery.parseJSON({});
+	});
+
+	var parsedValue = jsonParse.parse(null);
+	equal( parsedValue, null );
+
+	parsedValue = jQuery.parseJSON(null);
+	equal( parsedValue, null );
+
+	parsedValue = jsonParse.parse("{}");
+	equal( (typeof parsedValue === "object"), true );
+
+	parsedValue = jQuery.parseJSON("{}");
+	equal( (typeof parsedValue === "object"), true );
+	
+
+	window.JSON = jsonParse;
+} );
+