Add type: module to package.json

.esbuild/jisonTransformer.cjs

@@ -0,0 +1,14 @@
+const { Generator } = require('jison');
+exports.transformJison = (src) => {
+  const parser = new Generator(src, {
+    moduleType: 'js',
+    'token-stack': true,
+  });
+  const source = parser.generate({ moduleMain: '() => {}' });
+  const exporter = `
+	parser.parser = parser;
+	export { parser };
+	export default parser;
+	`;
+  return `${source} ${exporter}`;
+};

.esbuild/util.cjs

@@ -1,4 +1,4 @@
-const { Generator } = require('jison');
+const { transformJison } = require('./jisonTransformer.cjs');
 const fs = require('fs');
 const { dependencies } = require('../package.json');
 
@@ -93,9 +93,7 @@ const jisonPlugin = {
     build.onLoad({ filter: /\.jison$/ }, async (args) => {
       // Load the file from the file system
       const source = await fs.promises.readFile(args.path, 'utf8');
-      const contents = new Generator(source, { 'token-stack': true }).generate({
-        moduleMain: '() => {}', // disable moduleMain (default one requires Node.JS modules)
-      });
+      const contents = transformJison(source);
       return { contents, warnings: [] };
     });
   },

package.json

@@ -5,6 +5,7 @@
   "main": "dist/mermaid.core.mjs",
   "module": "dist/mermaid.core.mjs",
   "types": "dist/mermaid.d.ts",
+  "type": "module",
   "exports": {
     ".": {
       "require": "./dist/mermaid.min.js",