Use parcel for examples

Author: gberaudo

.gitignore

@@ -8,4 +8,4 @@ node_modules/
 /*.zip
 *.swp
 /*.tgz
-.parcel-cache
+.parcel-cache/

buildtools/fix_paths.js

@@ -0,0 +1,116 @@
+/**
+ * This file resolves extension-less imports to JS files if they exist, preserving sourcemaps.
+ * This allows to write extension-less imports in typescript files (which is required to allow transpilation).
+ * And still produces correctly resolving transpiled results, which can be used even without bundler.
+ * Note that we use inline sourcemaps here, as it is what we configure in tsconfig.json.
+ */
+import fs from 'fs';
+import path from 'path';
+
+import {parse, print} from 'recast';
+import * as typescript from 'recast/parsers/typescript.js';
+
+/**
+ *
+ * @param {string} dir
+ */
+async function* walk(dir) {
+  for await (const d of await fs.promises.opendir(dir)) {
+    const entry = path.join(dir, d.name);
+    if (d.isDirectory()) {yield* walk(entry);}
+    else if (d.isFile()) {yield entry;}
+  }
+}
+
+for await (const p of walk('lib')) {
+  if (p.endsWith('js')) {
+    console.log(p);
+    const source = fs.readFileSync(p);
+    const sourceMapPath = p + '.map';
+    let inputSourceMap;
+    if (fs.existsSync(sourceMapPath)) {
+      inputSourceMap = fs.readFileSync(sourceMapPath);
+    }
+    const ast = parse(source, {
+      sourceFileName: p,
+      parser: typescript,
+      inputSourceMap,
+    });
+    rewriteJSEnds(p, ast);
+
+    // Remove sourcemaps
+    const comments = ast.program.body.at(-1).comments;
+    const hasInlineSourceMap = comments && comments[0].value.startsWith('# sourceMappingURL=data:');
+    const hasExternalSourceMap = !hasInlineSourceMap && comments && comments[0].value.startsWith('# sourceMappingURL');
+    if (hasInlineSourceMap || hasExternalSourceMap) {
+      ast.program.body.at(-1).comments = undefined; // remove comment
+    }
+
+    // Output
+    const output = print(ast, {
+      sourceMapName: sourceMapPath
+    });
+    fs.writeFileSync(p, output.code);
+
+    // Write sourcemap
+    if (hasInlineSourceMap) {
+      const inlineSourceMap = `
+//# sourceMappingURL=data:application/json;base64,${btoa(JSON.stringify(output.map))}
+`;
+      fs.appendFileSync(p, inlineSourceMap);
+    } else if (hasExternalSourceMap) {
+      const externalSourceMap = `
+//# sourceMappingURL=${p}.map}
+`;
+      fs.appendFileSync(p, externalSourceMap);
+      fs.writeFileSync(`${p}.map`, JSON.stringify(output.map));
+    }
+  }
+}
+
+
+/**
+ *
+ * @param {string} source
+ * @return {string} if import rewritten
+ */
+function sourceRewrite(inFile, source) {
+  if (!source.startsWith('.')) {
+    return; // non relative paths are not in our project
+  }
+  const newSource = source + '.js';
+  const newsourcePath = path.join(path.dirname(inFile), newSource);
+  if (!fs.existsSync(newsourcePath)) {
+    return; // if there is no js there that means we should not rewrite it
+  }
+  return newSource;
+
+}
+
+/**
+ *
+ * @param {string} p path to the file
+ * @param {*} ast
+ */
+function rewriteJSEnds(p, ast) {
+  const body = ast.program.body;
+  for (const node of body) {
+    switch (node.type) {
+      case 'ImportDeclaration':
+      case 'ExportNamedDeclaration': {
+        if (!node.source) {
+          continue;
+        }
+        const source = node.source.value;
+        const newSource = sourceRewrite(p, source);
+        if (newSource) {
+          node.source.value = newSource;
+        }
+        break;
+      }
+      default: {
+        // pass
+      }
+    }
+  }
+}