Add option to control whether Babel is loaded. Closes #166

Author: Daniel15

src/React.Core/Exceptions/BabelNotLoadedException.cs

@@ -0,0 +1,46 @@
+/*
+ *  Copyright (c) 2014-2015, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant 
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+using System;
+using System.Runtime.Serialization;
+
+namespace React.Exceptions
+{
+	/// <summary>
+	/// Thrown when Babel is required but has not been loaded.
+	/// </summary>
+	[Serializable]
+	public class BabelNotLoadedException : ReactException
+	{
+		/// <summary>
+		/// Initializes a new instance of the <see cref="BabelNotLoadedException"/> class.
+		/// </summary>
+		public BabelNotLoadedException() : base(GetMessage()) { }
+
+		/// <summary>
+		/// Used by deserialization
+		/// </summary>
+		protected BabelNotLoadedException(SerializationInfo info, StreamingContext context)
+			: base(info, context)
+		{ }
+
+		/// <summary>
+		/// Gets a message that describes the current exception.
+		/// </summary>
+		private static string GetMessage()
+		{
+			return
+				"Babel has not been loaded, so JSX transformation can not be done. Please either " +
+				"transform your JavaScript files through an external tool (such as Babel, " +
+				"Webpack, Browserify or Gulp) and use the \"AddScriptWithoutTransform\" method to load " +
+				"them for server-side rendering, or enable the \"LoadBabel\" option in the ReactJS.NET " +
+				"configuration. Refer to the ReactJS.NET documentation for more details.";
+		}
+	}
+}

src/React.Core/IReactSiteConfiguration.cs

@@ -7,6 +7,7 @@
  *  of patent rights can be found in the PATENTS file in the same directory.
  */
 
+using System;
 using Newtonsoft.Json;
 using System.Collections.Generic;
 
@@ -123,6 +124,19 @@ public interface IReactSiteConfiguration
 		/// <returns>The configuration, for chaining</returns>
 		IReactSiteConfiguration SetLoadReact(bool loadReact);
 
+		/// <summary>
+		/// Gets or sets whether Babel is loading. Disabling the loading of Babel can improve startup
+		/// performance, but all your JSX files must be transformed beforehand (eg. through Babel,
+		/// Webpack or Browserify).
+		/// </summary>
+		bool LoadBabel { get; set; }
+		/// <summary>
+		/// Sets whether Babel is loading. Disabling the loading of Babel can improve startup
+		/// performance, but all your JSX files must be transformed beforehand (eg. through Babel,
+		/// Webpack or Browserify).
+		/// </summary>
+		IReactSiteConfiguration SetLoadBabel(bool loadBabel);
+
 		/// <summary>
 		/// Gets or sets the Babel configuration to use.
 		/// </summary>

src/React.Core/JavaScriptEngineFactory.cs

@@ -100,7 +100,9 @@ protected virtual void InitialiseEngine(IJsEngine engine)
 			{
 				engine.ExecuteResource("React.Resources.react-with-addons.js", thisAssembly);
 				engine.Execute("React = global.React");
-				// TODO: Make this configurable, so we don't load Babel if it's not needed.
+			}
+			if (_config.LoadBabel)
+			{
 				engine.ExecuteResource("React.node_modules.babel_core.browser.js", thisAssembly);
 			}
 

src/React.Core/JsxTransformer.cs

@@ -253,6 +253,7 @@ protected virtual JavaScriptWithSourceMap TransformJsxWithHeader(
 		/// <returns>JavaScript</returns>
 		public virtual string TransformJsx(string input, string filename = "unknown")
 		{
+			EnsureBabelLoaded();
 			try
 			{
 				var output = _environment.ExecuteWithLargerStackIfRequired<string>(
@@ -281,6 +282,7 @@ public virtual JavaScriptWithSourceMap TransformJsxWithSourceMap(
 			string filename = "unknown"
 		)
 		{
+			EnsureBabelLoaded();
 			try
 			{
 				return _environment.ExecuteWithLargerStackIfRequired<JavaScriptWithSourceMap>(
@@ -356,5 +358,16 @@ string filename
 			_fileSystem.WriteAsString(sourceMapPath, result.SourceMap == null ? string.Empty : result.SourceMap.ToJson());
 			return outputPath;
 		}
+
+		/// <summary>
+		/// Ensures that Babel has been loaded into the JavaScript engine.
+		/// </summary>
+		private void EnsureBabelLoaded()
+		{
+			if (!_config.LoadBabel)
+			{
+				throw new BabelNotLoadedException();
+			}
+		}
 	}
 }

src/React.Core/React.Core.csproj

@@ -90,6 +90,7 @@
     </Compile>
     <Compile Include="AssemblyRegistration.cs" />
     <Compile Include="BabelConfig.cs" />
+    <Compile Include="Exceptions\BabelNotLoadedException.cs" />
     <Compile Include="Exceptions\ReactNotInitialisedException.cs" />
     <Compile Include="FileSystemExtensions.cs" />
     <Compile Include="JavaScriptEngineUtils.cs" />

src/React.Core/ReactSiteConfiguration.cs

@@ -36,6 +36,7 @@ public ReactSiteConfiguration()
 			BabelConfig = new BabelConfig();
 			ReuseJavaScriptEngines = true;
 			AllowMsieEngine = true;
+			LoadBabel = true;
 			LoadReact = true;
 			JsonSerializerSettings = new JsonSerializerSettings
 			{
@@ -220,6 +221,24 @@ public IReactSiteConfiguration SetLoadReact(bool loadReact)
 			return this;
 		}
 
+		/// <summary>
+		/// Gets or sets whether Babel is loading. Disabling the loading of Babel can improve startup
+		/// performance, but all your JSX files must be transformed beforehand (eg. through Babel,
+		/// Webpack or Browserify).
+		/// </summary>
+		public bool LoadBabel { get; set; }
+
+		/// <summary>
+		/// Sets whether Babel is loading. Disabling the loading of Babel can improve startup
+		/// performance, but all your JSX files must be transformed beforehand (eg. through Babel,
+		/// Webpack or Browserify).
+		/// </summary>
+		public IReactSiteConfiguration SetLoadBabel(bool loadBabel)
+		{
+			LoadBabel = loadBabel;
+			return this;
+		}
+
 		/// <summary>
 		/// Gets or sets the Babel configuration to use.
 		/// </summary>