Give the user a warning when using unoptimized JSX code and send the user to the correct location in the documentation to optimize.

Author: SanderSpies

docs/docs/08-tooling-integration.md

@@ -20,7 +20,7 @@ We provide CDN-hosted versions of React [on our download page](/react/downloads.
 
 We have instructions for building from `master` [in our GitHub repository](https://github.com/facebook/react). We build a tree of CommonJS modules under `build/modules` which you can drop into any environment or packaging tool that supports CommonJS.
 
-## JSX
+## <a id="jsx">JSX</a>
 
 ### In-browser JSX Transform
 

vendor/browser-transforms.js

@@ -51,6 +51,7 @@ var load = exports.load = function(url, callback) {
   var xhr;
   xhr = window.ActiveXObject ? new window.ActiveXObject('Microsoft.XMLHTTP')
                              : new XMLHttpRequest();
+
   // Disable async since we need to execute scripts in the order they are in the
   // DOM to mirror normal script loading.
   xhr.open('GET', url, false);
@@ -79,6 +80,10 @@ runScripts = function() {
     return script.type === 'text/jsx';
   });
 
+  if(jsxScripts.length){
+    console.warn("You are using unoptimized JSX (to optimize for production see: http://facebook.github.io/react/docs/tooling-integration.html#jsx)");
+  }
+
   jsxScripts.forEach(function(script) {
     if (script.src) {
       load(script.src);