Build .cjs bundles from ES5+modules code, for back compat.

Author: benjamn

.npmignore

@@ -6,4 +6,5 @@
 .reify-cache
 tsconfig.json
 tsconfig.rollup.json
+tsconfig.es5.json
 rollup.config.js

package.json

@@ -28,7 +28,8 @@
     "url": "https://github.com/benjamn/optimism/issues"
   },
   "scripts": {
-    "build": "npm run clean && tsc && rollup -c",
+    "build": "npm run clean && npm run tsc:es5 && tsc && rollup -c && rimraf lib/es5",
+    "tsc:es5": "tsc -p tsconfig.es5.json",
     "clean": "rimraf lib",
     "prepare": "npm run build",
     "mocha": "mocha --require source-map-support/register --reporter spec --full-trace",

rollup.config.js

@@ -26,7 +26,7 @@ function build(input, output, format) {
 
 export default [
   build(
-    "lib/index.js",
+    "lib/es5/index.js",
     "lib/bundle.cjs",
     "cjs"
   ),
@@ -36,7 +36,7 @@ export default [
     "esm"
   ),
   build(
-    "lib/tests/main.js",
+    "lib/es5/tests/main.js",
     "lib/tests/bundle.cjs",
     "cjs"
   ),

tsconfig.es5.json

@@ -0,0 +1,8 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "target": "es5",
+    "module": "es2015",
+    "outDir": "lib/es5"
+  }
+}