From 3b4a7cbd582ffb6d0fc7f9ec2781fe1cafb2c935 Mon Sep 17 00:00:00 2001
From: Evad37 <evad37@gmail.com>
Date: Sat, 2 Feb 2019 13:42:00 +0800
Subject: [PATCH] resourceloader: Add getScript() method for loading scripts
 with callback

Provides a friendly wrapper for loading scripts using $.ajax().
Returns a promise when the script dependency -- a single
script url -- has been loaded. This matches how mw.loader.load
is able to load a script url, and how mw.loader.using will
return a promised that is resolved when dependecies are loaded,
or rejected if there is an error.

Added as a separate function mw.loader.getScript(), rather
than adding this functionality to using(), as it is a separate
use case, less confusing for users, and there is no shared or
duplicated code between loading a script and loading one
or more named modules.

Bug: T27962
Change-Id: I13be426d03261a2d0c6a1631af94a9f9af58394b
---
 .../src/mediawiki.base/mediawiki.base.js      | 37 +++++++++++++++++--
 .../mediawiki.loader.getScript.example.js     |  1 +
 .../mediawiki/mediawiki.loader.test.js        | 21 +++++++++++
 3 files changed, 55 insertions(+), 4 deletions(-)
 create mode 100644 tests/qunit/data/mediawiki.loader.getScript.example.js

diff --git a/resources/src/mediawiki.base/mediawiki.base.js b/resources/src/mediawiki.base/mediawiki.base.js
index 107ab33fb6..9016c7c274 100644
--- a/resources/src/mediawiki.base/mediawiki.base.js
+++ b/resources/src/mediawiki.base/mediawiki.base.js
@@ -644,7 +644,7 @@
 		var deferred = $.Deferred();
 
 		// Allow calling with a single dependency as a string
-		if ( typeof dependencies === 'string' ) {
+		if ( !Array.isArray( dependencies ) ) {
 			dependencies = [ dependencies ];
 		}
 
@@ -662,13 +662,42 @@
 			return deferred.reject( e ).promise();
 		}
 
-		mw.loader.enqueue( dependencies, function () {
-			deferred.resolve( mw.loader.require );
-		}, deferred.reject );
+		mw.loader.enqueue(
+			dependencies,
+			function () { deferred.resolve( mw.loader.require ); },
+			deferred.reject
+		);
 
 		return deferred.promise();
 	};
 
+	/**
+	 * Load a script by URL.
+	 *
+	 * Example:
+	 *
+	 *     mw.loader.getScript(
+	 *         'https://example.org/x-1.0.0.js'
+	 *     )
+	 *         .then( function () {
+	 *             // Script succeeded. You can use X now.
+	 *         }, function ( e ) {
+	 *             // Script failed. X is not avaiable
+	 *             mw.log.error( e.message ); // => "Failed to load script"
+	 *         } );
+	 *     } );
+	 *
+	 * @member mw.loader
+	 * @param {string} url Script URL
+	 * @return {jQuery.Promise} Resolved when the script is loaded
+	 */
+	mw.loader.getScript = function ( url ) {
+		return $.ajax( url, { dataType: 'script', cache: true } )
+			.catch( function () {
+				throw new Error( 'Failed to load script' );
+			} );
+	};
+
 	// Alias $j to jQuery for backwards compatibility
 	// @deprecated since 1.23 Use $ or jQuery instead
 	mw.log.deprecate( window, '$j', $, 'Use $ or jQuery instead.' );
diff --git a/tests/qunit/data/mediawiki.loader.getScript.example.js b/tests/qunit/data/mediawiki.loader.getScript.example.js
new file mode 100644
index 0000000000..e5e4759d1c
--- /dev/null
+++ b/tests/qunit/data/mediawiki.loader.getScript.example.js
@@ -0,0 +1 @@
+mw.getScriptExampleScriptLoaded = true;
diff --git a/tests/qunit/suites/resources/mediawiki/mediawiki.loader.test.js b/tests/qunit/suites/resources/mediawiki/mediawiki.loader.test.js
index cb028a93a1..8b06bd6e1f 100644
--- a/tests/qunit/suites/resources/mediawiki/mediawiki.loader.test.js
+++ b/tests/qunit/suites/resources/mediawiki/mediawiki.loader.test.js
@@ -24,6 +24,7 @@
 			// exposed for cross-file mocks.
 			delete mw.loader.testCallback;
 			delete mw.loader.testFail;
+			delete mw.getScriptExampleScriptLoaded;
 		}
 	} ) );
 
@@ -1097,4 +1098,24 @@
 		} );
 	} );
 
+	QUnit.test( '.getScript() - success', function ( assert ) {
+		var scriptUrl = QUnit.fixurl(
+			mw.config.get( 'wgScriptPath' ) + '/tests/qunit/data/mediawiki.loader.getScript.example.js'
+		);
+
+		return mw.loader.getScript( scriptUrl ).then(
+			function () {
+				assert.strictEqual( mw.getScriptExampleScriptLoaded, true, 'Data attached to a global object is available' );
+			}
+		);
+	} );
+
+	QUnit.test( '.getScript() - failure', function ( assert ) {
+		assert.rejects(
+			mw.loader.getScript( 'https://example.test/not-found' ),
+			/Failed to load script/,
+			'Descriptive error message'
+		);
+	} );
+
 }() );
-- 
2.20.1