Core: Warn against using jQuery.parseJSON, remove old hacks around this method

Fixes #150
Refs jquery/jquery#2800
Refs #152

Author: mgol

Gruntfile.js

@@ -24,7 +24,6 @@ module.exports = function( grunt ) {
 			"src/attributes.js",
 			"src/core.js",
 			"src/css.js",
-			"src/ajax.js",
 			"src/data.js",
 			"src/manipulation.js",
 			"src/effects.js",

src/ajax.js

@@ -1,7 +1,6 @@
 
 var matched, browser,
 	oldInit = jQuery.fn.init,
-	oldParseJSON = jQuery.parseJSON,
 	rspaceAngle = /^\s*</,
 	rattrHash = /\[\s*\w+\s*[~|^$*]?=\s*(?![\s'"])[^#\]]*#/,
 
@@ -76,15 +75,6 @@ jQuery.fn.init = function( selector, context, rootjQuery ) {
 };
 jQuery.fn.init.prototype = jQuery.fn;
 
-// Let $.parseJSON(falsy_value) return null
-jQuery.parseJSON = function( json ) {
-	if ( !json ) {
-		migrateWarn( "jQuery.parseJSON requires a valid JSON string" );
-		return null;
-	}
-	return oldParseJSON.apply( this, arguments );
-};
-
 jQuery.uaMatch = function( ua ) {
 	ua = ua.toLowerCase();
 
@@ -159,3 +149,8 @@ jQuery.fn.size = function() {
 	migrateWarn( "jQuery.fn.size() is deprecated; use the .length property" );
 	return this.length;
 };
+
+jQuery.parseJSON = function() {
+	migrateWarn( "jQuery.parseJSON is deprecated; use JSON.parse" );
+	return JSON.parse.apply( null, arguments );
+};

src/core.js

@@ -212,29 +212,6 @@ test( "jQuery( '<element>' ) usable on detached elements (#128)", function() {
 	ok( true, "No crash when operating on detached elements with window" );
 } );
 
-test( "jQuery.parseJSON() falsy values", function() {
-	expect( 6 );
-
-	expectNoWarning( "valid JSON", function() {
-		jQuery.parseJSON( "{\"a\":1}" );
-	} );
-	expectWarning( "actual null", function() {
-		jQuery.parseJSON( null );
-	} );
-	expectNoWarning( "string null", function() {
-		jQuery.parseJSON( "null" );
-	} );
-	expectWarning( "empty string", function() {
-		jQuery.parseJSON( "" );
-	} );
-	expectWarning( "Boolean false", function() {
-		jQuery.parseJSON( false );
-	} );
-	expectWarning( "undefined", function() {
-		jQuery.parseJSON( undefined );
-	} );
-} );
-
 test( "jQuery.browser", function() {
 	expect( 3 );
 
@@ -386,3 +363,15 @@ test( ".size", function() {
         jQuery( "<div />" ).size();
     } );
 } );
+
+test( "jQuery.parseJSON", function() {
+    expect( 2 );
+
+    expectWarning( "jQuery.parseJSON", function() {
+		deepEqual(
+			jQuery.parseJSON( "{\"a\":1}" ),
+			{ a: 1 },
+			"jQuery.parseJSON output"
+		);
+    } );
+} );

test/ajax.js

@@ -39,7 +39,6 @@
 	<script src="data.js"></script>
 	<script src="attributes.js"></script>
 	<script src="manipulation.js"></script>
-	<script src="ajax.js"></script>
 	<script src="event.js"></script>
 	<script src="traversing.js"></script>
 	<script src="deferred.js"></script>

test/core.js

@@ -56,26 +56,6 @@ This is _not_ a warning, but a console log message the plugin shows when it firs
 
 **Solution:** Do not use jQuery in Quirks mode, it has never been supported. See the previous item for solutions.
 
-### JQMIGRATE: jQuery.parseJSON requires a valid JSON string
-
-**Cause**: Before jQuery 1.9.0, the `$.parseJSON()` method allowed some invalid JSON strings and returned `null` as a result without throwing an error. This put it at odds with the `JSON.parse()` method. The two methods are aligned as of 1.9.0 and values such as an empty string are properly not considered valid by `$.parseJSON()`.
-
-**Solution:** If you want to consider values such as `""` or `false` successful and treat them as `null`, check for them before calling `$.parseJSON()`. Since falsy values such as an empty string were previously returned as a `null` without complaint, this code will suffice in most cases:
-```js
-var json = $.parseJSON(jsonString || "null");
-```
-If your own code is not calling `$.parseJSON()` directly, it is probably using AJAX to retrieve a JSON value from a server that is returning an empty string in the content body rather than a valid JSON response such as `null` or `{}`. If it isn't possible to correct the invalid JSON in the server response, you can retrieve the response as text:
-```js
-$.ajax({
-    url: "...",
-    dataType: "text",
-    success: function( text ) {
-        var json = text? $.parseJSON(text) : null;
-        ...
-    }
-});
-```
-
 ### JQMIGRATE: jQuery.browser is deprecated
 
 **Cause:** `jQuery.browser` was deprecated in version 1.3, and finally removed in 1.9. Browser sniffing is notoriously unreliable as means of detecting whether to implement particular features.
@@ -240,3 +220,9 @@ jQuery.easing.easeInCubic = function ( p ) {
 ```
 
 See jQuery-ui [commit](https://github.com/jquery/jquery-ui/commit/c0093b599fcd58b6ad122ab425c4cc1a4da4a520#diff-9cd789a170c765edcf0f4854db386e1a) for other possible cases.
+
+### JQMIGRATE: jQuery.parseJSON is deprecated; use JSON.parse
+
+**Cause**: The `jQuery.parseJSON` method in recent jQuery is identical to the native `JSON.parse`. As of jQuery 3.0 `jQuery.parseJSON` is deprecated.
+
+**Solution**: Replace any use of `jQuery.parseJSON` with `JSON.parse`.