add CommonJS (CJS) compatibility

.babelrc

@@ -0,0 +1,17 @@
+{
+  "presets": [
+    [
+      "@babel/preset-env",
+      {
+        "targets": {
+          "node": "current"
+        },
+        "modules": "commonjs"
+      }
+    ]
+  ],
+  "plugins": [
+    "add-module-exports"
+  ],
+  "sourceMaps": true
+}

.gitignore

@@ -1,3 +1,5 @@
+dist/
+
 .yarn/*
 !.yarn/patches
 !.yarn/plugins

.mocharc.cjs.json

@@ -0,0 +1,7 @@
+{
+  "extension": ["js"],
+  "spec": ["test/cjs/*.{test,spec}.cjs", "test/package.test.cjs"],
+  "require": ["@babel/register"],
+  "timeout": 60000,
+  "exit": true
+}

.mocharc.esm.json

@@ -0,0 +1,6 @@
+{
+  "extension": ["mjs"],
+  "spec": "test/**/*.{test,spec}.mjs",
+  "timeout": 60000,
+  "exit": true
+}