modified

build/node_modules/assets-webpack-plugin/dist/lib/output/createQueuedWriter.js

@@ -0,0 +1,34 @@
+"use strict";
+
+/**
+ * Takes in a processor function, and returns a writer function.
+ *
+ * @param {Function} processor
+ *
+ * @return {Function} queuedWriter
+ */
+module.exports = function createQueuedWriter(processor) {
+  var queue = [];
+
+  var iterator = function iterator(callback) {
+    return function (err) {
+      queue.shift();
+      callback(err);
+
+      var next = queue[0];
+      if (next) {
+        processor(next.fs, next.data, iterator(next.callback));
+      }
+    };
+  };
+
+  return function queuedWriter(fs, data, callback) {
+    var empty = !queue.length;
+    queue.push({ fs: fs, data: data, callback: callback });
+
+    if (empty) {
+      // start processing
+      processor(fs, data, iterator(callback));
+    }
+  };
+};