From f38f88d0d39a69cff9a944f7e2d1848ba991291a Mon Sep 17 00:00:00 2001
From: =?utf8?q?Bartosz=20Dziewo=C5=84ski?= <matma.rex@gmail.com>
Date: Tue, 29 Jan 2019 04:33:14 +0100
Subject: [PATCH] resourceloader: Reduce 'implement' overhead for modules
 without scripts

Change-Id: I55728c526711545be3923d3e1e2f276cbfa52224
---
 includes/resourceloader/ResourceLoader.php                | 4 +++-
 resources/src/startup/mediawiki.js                        | 5 ++++-
 .../resourceloader/ResourceLoaderClientHtmlTest.php       | 8 ++++----
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/includes/resourceloader/ResourceLoader.php b/includes/resourceloader/ResourceLoader.php
index b7c85d43b1..b64826063c 100644
--- a/includes/resourceloader/ResourceLoader.php
+++ b/includes/resourceloader/ResourceLoader.php
@@ -1218,7 +1218,9 @@ MESSAGE;
 		$name, $scripts, $styles, $messages, $templates
 	) {
 		if ( $scripts instanceof XmlJsCode ) {
-			if ( self::inDebugMode() ) {
+			if ( $scripts->value === '' ) {
+				$scripts = null;
+			} elseif ( self::inDebugMode() ) {
 				$scripts = new XmlJsCode( "function ( $, jQuery, require, module ) {\n{$scripts->value}\n}" );
 			} else {
 				$scripts = new XmlJsCode( 'function($,jQuery,require,module){' . $scripts->value . '}' );
diff --git a/resources/src/startup/mediawiki.js b/resources/src/startup/mediawiki.js
index 967c52992a..b5ba6a66a6 100644
--- a/resources/src/startup/mediawiki.js
+++ b/resources/src/startup/mediawiki.js
@@ -2341,9 +2341,11 @@
 
 						try {
 							if ( typeof descriptor.script === 'function' ) {
+								// Function literal: cast to string
 								encodedScript = String( descriptor.script );
 							} else if (
-								// Plain object: an object that is not null and is not an array
+								// Plain object: serialise as object literal (not JSON),
+								// making sure to preserve the functions.
 								typeof descriptor.script === 'object' &&
 								descriptor.script &&
 								!Array.isArray( descriptor.script )
@@ -2358,6 +2360,7 @@
 									} ).join( ',' ) +
 									'}}';
 							} else {
+								// Array of urls, or null.
 								encodedScript = JSON.stringify( descriptor.script );
 							}
 							args = [
diff --git a/tests/phpunit/includes/resourceloader/ResourceLoaderClientHtmlTest.php b/tests/phpunit/includes/resourceloader/ResourceLoaderClientHtmlTest.php
index dbc757f90b..70056baf62 100644
--- a/tests/phpunit/includes/resourceloader/ResourceLoaderClientHtmlTest.php
+++ b/tests/phpunit/includes/resourceloader/ResourceLoaderClientHtmlTest.php
@@ -225,7 +225,7 @@ Deprecation message.' ]
 			. '<script>(window.RLQ=window.RLQ||[]).push(function(){'
 			. 'mw.config.set({"key":"value"});'
 			. 'mw.loader.state({"test.exempt":"ready","test.private":"loading","test.styles.pure":"ready","test.styles.private":"ready","test.styles.deprecated":"ready","test.scripts":"loading"});'
-			. 'mw.loader.implement("test.private@{blankVer}",function($,jQuery,require,module){},{"css":[]});'
+			. 'mw.loader.implement("test.private@{blankVer}",null,{"css":[]});'
 			. 'RLPAGEMODULES=["test"];mw.loader.load(RLPAGEMODULES);'
 			. 'mw.loader.load("/w/load.php?debug=false\u0026lang=nl\u0026modules=test.scripts\u0026only=scripts\u0026skin=fallback");'
 			. '});</script>' . "\n"
@@ -343,7 +343,7 @@ Deprecation message.' ]
 				'context' => [],
 				'modules' => [ 'test.private' ],
 				'only' => ResourceLoaderModule::TYPE_COMBINED,
-				'output' => '<script>(window.RLQ=window.RLQ||[]).push(function(){mw.loader.implement("test.private@{blankVer}",function($,jQuery,require,module){},{"css":[]});});</script>',
+				'output' => '<script>(window.RLQ=window.RLQ||[]).push(function(){mw.loader.implement("test.private@{blankVer}",null,{"css":[]});});</script>',
 			],
 			[
 				'context' => [],
@@ -393,7 +393,7 @@ Deprecation message.' ]
 				'context' => [],
 				'modules' => [ 'test.shouldembed' ],
 				'only' => ResourceLoaderModule::TYPE_COMBINED,
-				'output' => '<script>(window.RLQ=window.RLQ||[]).push(function(){mw.loader.implement("test.shouldembed@09p30q0",function($,jQuery,require,module){},{"css":[]});});</script>',
+				'output' => '<script>(window.RLQ=window.RLQ||[]).push(function(){mw.loader.implement("test.shouldembed@09p30q0",null,{"css":[]});});</script>',
 			],
 			[
 				'context' => [],
@@ -411,7 +411,7 @@ Deprecation message.' ]
 				'context' => [],
 				'modules' => [ 'test', 'test.shouldembed' ],
 				'only' => ResourceLoaderModule::TYPE_COMBINED,
-				'output' => '<script>(window.RLQ=window.RLQ||[]).push(function(){mw.loader.load("/w/load.php?debug=false\u0026lang=nl\u0026modules=test\u0026skin=fallback");mw.loader.implement("test.shouldembed@09p30q0",function($,jQuery,require,module){},{"css":[]});});</script>',
+				'output' => '<script>(window.RLQ=window.RLQ||[]).push(function(){mw.loader.load("/w/load.php?debug=false\u0026lang=nl\u0026modules=test\u0026skin=fallback");mw.loader.implement("test.shouldembed@09p30q0",null,{"css":[]});});</script>',
 			],
 			[
 				'context' => [],
-- 
2.20.1