feat(builtins): load min versions if available

src/packagers/JSConcatPackager.js

@@ -1,27 +1,15 @@
 const Packager = require('./Packager');
 const path = require('path');
-const fs = require('fs');
 const concat = require('../scope-hoisting/concat');
 const urlJoin = require('../utils/urlJoin');
+const getExisting = require('../utils/getExisting');
 const walk = require('babylon-walk');
 const babylon = require('babylon');
 const t = require('babel-types');
 const {getName, getIdentifier} = require('../scope-hoisting/utils');
 
-const prelude = {
-  source: fs
-    .readFileSync(path.join(__dirname, '../builtins/prelude2.js'), 'utf8')
-    .trim(),
-  minified: fs
-    .readFileSync(path.join(__dirname, '../builtins/prelude2.min.js'), 'utf8')
-    .trim()
-    .replace(/;$/, '')
-};
-
-const helpers =
-  fs
-    .readFileSync(path.join(__dirname, '../builtins/helpers.js'), 'utf8')
-    .trim() + '\n';
+const prelude = getExisting(path.join(__dirname, '../builtins/prelude2'));
+const helpers = getExisting(path.join(__dirname, '../builtins/helpers'));
 
 class JSConcatPackager extends Packager {
   async start() {

src/packagers/JSPackager.js

@@ -1,19 +1,11 @@
-const fs = require('fs');
 const path = require('path');
 const Packager = require('./Packager');
+const getExisting = require('../utils/getExisting');
 const urlJoin = require('../utils/urlJoin');
 const lineCounter = require('../utils/lineCounter');
 const objectHash = require('../utils/objectHash');
 
-const prelude = {
-  source: fs
-    .readFileSync(path.join(__dirname, '../builtins/prelude.js'), 'utf8')
-    .trim(),
-  minified: fs
-    .readFileSync(path.join(__dirname, '../builtins/prelude.min.js'), 'utf8')
-    .trim()
-    .replace(/;$/, '')
-};
+const prelude = getExisting(path.join(__dirname, '../builtins/prelude'));
 
 class JSPackager extends Packager {
   async start() {

src/utils/getExisting.js

@@ -0,0 +1,21 @@
+const fs = require('fs');
+/**
+ * Creates an object for source and a minified source
+ * e.g. builtins.min.js and builtins.js.
+ * If the first argument does not have an extension it will
+ * try use min.js and .js with .js as the minified fallback
+ */
+module.exports = function(minified, source) {
+  if(minified.split('.').length < 2 && source === undefined) {
+    source = minified + '.js';
+    minified = minified + 'min.js';
+  }
+  var sourceFile = fs.readFileSync(source, 'utf8').trim();
+  return {
+    source: sourceFile,
+    minified: fs.existsSync(minified) ? fs
+      .readFileSync(minified, 'utf8')
+      .trim()
+      .replace(/;$/, '') : sourceFile
+  }
+};