default to spec mode for template literal transform

packages/babel-plugin-transform-es2015-template-literals/README.md

@@ -42,8 +42,7 @@ With options:
 {
   "plugins": [
     ["transform-es2015-template-literals", {
-      "loose": true,
-      "spec": true
+      "loose": true
     }]
   ]
 }
@@ -69,22 +68,24 @@ require("babel-core").transform("code", {
 
 `boolean`, defaults to `false`.
 
-In loose mode, tagged template literal objects aren't frozen.
+When `true`, tagged template literal objects aren't frozen. All template literal expressions and quasis are combined with the `+` operator instead of with `String.prototype.concat`.
 
-### `spec`
-
-`boolean`, defaults to `false`.
-
-This option combines all template literal expressions and quasis with `String.prototype.concat`. It will handle cases with `Symbol.toPrimitive` correctly and throw correctly if template literal expression is a `Symbol()`. See [babel/babel#5791](https://github.com/babel/babel/pull/5791).
+When `false` or not set, combines all template literal expressions and quasis with `String.prototype.concat`. It will handle cases with `Symbol.toPrimitive` correctly and throw correctly if template literal expression is a `Symbol()`. See [babel/babel#5791](https://github.com/babel/babel/pull/5791).
 
 **In**
 
 ```javascript
 `foo${bar}baz${quux}${1}`;
 ```
 
-**Out**
+**Out (without `{"loose": true}`)**
 
 ```javascript
 "foo".concat(bar, "baz").concat(quux, 1);
 ```
+
+**Out (with `{"loose": true}`)**
+
+```javascript
+"foo" + bar + "baz" + quux + 1;
+```

packages/babel-plugin-transform-es2015-template-literals/src/index.js

@@ -75,20 +75,20 @@ export default function({ types: t }) {
         // since `+` is left-to-right associative
         // ensure the first node is a string if first/second isn't
         const considerSecondNode =
-          state.opts.spec || !t.isStringLiteral(nodes[1]);
+          !state.opts.loose || !t.isStringLiteral(nodes[1]);
         if (!t.isStringLiteral(nodes[0]) && considerSecondNode) {
           nodes.unshift(t.stringLiteral(""));
         }
         let root = nodes[0];
 
-        if (state.opts.spec) {
-          if (nodes.length > 1) {
-            root = buildConcatCallExressions(nodes);
-          }
-        } else {
+        if (state.opts.loose) {
           for (let i = 1; i < nodes.length; i++) {
             root = t.binaryExpression("+", root, nodes[i]);
           }
+        } else {
+          if (nodes.length > 1) {
+            root = buildConcatCallExressions(nodes);
+          }
         }
 
         path.replaceWith(root);

packages/babel-plugin-transform-es2015-template-literals/test/fixtures/loose/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-es2015-template-literals", {"loose": true}]]
+}

packages/babel-plugin-transform-es2015-template-literals/test/fixtures/loose/tag/expected.js

@@ -0,0 +1,5 @@
+var _templateObject = _taggedTemplateLiteralLoose(["wow\na", "b ", ""], ["wow\\na", "b ", ""]);
+
+function _taggedTemplateLiteralLoose(strings, raw) { strings.raw = raw; return strings; }
+
+var foo = bar(_templateObject, 42, _.foobar());