[ESM] Convert the external/builder/-folder to use standard modules

external/webpack/pdfjsdev-loader.mjs

@@ -0,0 +1,41 @@
+/* Copyright 2017 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import path from "path";
+import { preprocessPDFJSCode } from "../builder/preprocessor2.mjs";
+
+export default function (source) {
+  // Options must be specified, ignoring request if not.
+  if (!this.query || typeof this.query !== "object") {
+    return source;
+  }
+  this.cacheable();
+
+  const filePath = this.resourcePath;
+  const context = this.rootContext;
+  const sourcePath = path.relative(context, filePath).split(path.sep).join("/");
+
+  const ctx = Object.create(this.query);
+  ctx.sourceMap = true;
+  ctx.sourceFile = sourcePath;
+
+  const callback = this.callback;
+  const sourceAndMap = preprocessPDFJSCode(ctx, source);
+  const map = sourceAndMap.map.toJSON();
+  // escodegen does not embed source -- setting map's sourcesContent.
+  map.sourcesContent = [source];
+  callback(null, sourceAndMap.code, map);
+  return undefined;
+}