fix(merge-sibling-var): recalculate dedeclaratios when concatenating …

…variables (#826)
babel · May 1, 2018 · 5527669 · 5527669
1 parent b5bafae
commit 5527669
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Showing 2 changed files with 36 additions and 3 deletions.
diff --git a/packages/babel-plugin-transform-merge-sibling-variables/src/index.js b/packages/babel-plugin-transform-merge-sibling-variables/src/index.js
@@ -57,14 +57,24 @@ module.exports = function({ types: t }) {
 
             let sibling = path.getSibling(path.key + 1);
 
+            let declarations = [];
+
             while (sibling.isVariableDeclaration({ kind: node.kind })) {
-              node.declarations = node.declarations.concat(
-                sibling.node.declarations
-              );
+              declarations = declarations.concat(sibling.node.declarations);
+
               sibling.remove();
 
               sibling = path.getSibling(path.key + 1);
             }
+
+            if (declarations.length > 0) {
+              path.replaceWith(
+                t.variableDeclaration(node.kind, [
+                  ...node.declarations,
+                  ...declarations
+                ])
+              );
+            }
           },
 
           // concat `var` declarations next to for loops with it's initialisers.

diff --git a/packages/babel-preset-minify/__tests__/minify-env-tests.js b/packages/babel-preset-minify/__tests__/minify-env-tests.js
@@ -158,4 +158,27 @@ describe("preset along with env", () => {
       }
     `
   );
+
+  thePlugin(
+    "should fix issue#825-merge-sibling-vars",
+    `
+    (function() {
+      const blah = 71;
+
+      var start = 1, navx = '';
+      while (start < 71) {
+          navx += 'a';
+          start += 10;
+      }
+      return 'b' + navx;
+    })();
+  `,
+    `
+    (function () {
+      for (var a = 1, b = ''; 71 > a;) b += 'a', a += 10;
+
+      return 'b' + b;
+    })();
+  `
+  );
 });