Hot module replacement

hotModuleReplacement.js

@@ -0,0 +1,36 @@
+function forceRedraw(element) {
+    var n = document.createTextNode(' ');
+    var visibility = element.style.visibility; 
+    element.appendChild(n);
+    element.style.visibility = 'hidden';
+    setTimeout(function(){
+        element.style.visibility = visibility;
+        n.parentNode.removeChild(n);
+    }, 20);
+}
+
+function replaceStylesheet(styleSheet, url) {
+  // Wait until the extract module is complete
+  styleSheet.href = url;
+  setTimeout(function() {
+    console.log('[HMR]', 'Reload css: ', url);
+    forceRedraw(document.body);
+  }, 100);
+}
+
+module.exports = function(compilationHash, outputFilename) {
+  if (document) {
+    var styleSheets = document.getElementsByTagName('link');
+    for (var i = 0; i < styleSheets.length; i++) {
+      if (styleSheets[i].href) {
+        var hrefUrl = styleSheets[i].href.split('?');
+        var href = hrefUrl[0];
+        var hash = hrefUrl[1];
+        if (hash !== compilationHash && href === document.location.origin + '/' + outputFilename) {
+          replaceStylesheet(styleSheets[i], href + '?' + compilationHash);
+          break;
+        }
+      }
+    }
+  }
+}

index.js

@@ -298,6 +298,12 @@ ExtractTextPlugin.prototype.apply = function(compiler) {
 					});
 					compilation.assets[file] = source;
 					chunk.files.push(file);
+
+					// Hot module replacement
+					extractedChunk.modules.forEach(function(module){
+						var originalModule = module.getOriginalModule();
+						originalModule._source._value = originalModule._source._value.replace('%%extracted-file%%', file);
+					});
 				}
 			}, this);
 			callback();

loader.js

@@ -105,8 +105,12 @@ module.exports.pitch = function(request) {
 						});
 					});
 					this[__dirname](text, query);
-					if(text.locals && typeof resultSource !== "undefined") {
-						resultSource += "\nmodule.exports = " + JSON.stringify(text.locals) + ";";
+					if (resultSource !== "undefined") {
+						if(text.locals) {
+							resultSource += "\nmodule.exports = " + JSON.stringify(text.locals) + ";";
+						}
+						resultSource += '\nif(module.hot){require("' + require.resolve('./hotModuleReplacement.js') + '")' +
+							'("' + compilation.hash + '", "%%extracted-file%%");}'
 					}
 				} catch(e) {
 					return callback(e);