add esm bundle

build.js

@@ -0,0 +1,45 @@
+#!/usr/bin/env node
+"use strict";
+
+const fs = require("fs");
+const browserify = require("browserify");
+const pkg = require("./package.json");
+const timers = require("./src/fake-timers-src.js");
+
+function makeBundle(entryPoint, config, done) {
+    browserify(entryPoint, config).bundle((err, buffer) => {
+        if (err) {
+            throw err;
+        }
+        done(buffer.toString());
+    });
+}
+
+makeBundle(
+    "./src/fake-timers-src.js",
+    {
+        standalone: "FakeTimers",
+        detectGlobals: false
+    },
+    (bundle) => {
+        fs.writeFileSync("fake-timers.js", bundle);
+    }
+);
+
+makeBundle(
+    "./src/fake-timers-esm.js",
+    {
+        detectGlobals: false
+    },
+    (bundle) => {
+        let source = `let FakeTimers;\n`;
+        source += bundle;
+        source += Object.keys(timers)
+            .map((key) =>
+                `const _${key} = FakeTimers.${key};` +
+                `\nexport { _${key} as ${key} };`)
+            .join("\n");
+
+        fs.writeFileSync("fake-timers-esm.js", source);
+    }
+);