Destructuring: Fix array unpacking assignments with holes on RHS

babel · Jan 26, 2019 · 0ecb9ca · 0ecb9ca
1 parent 7dc157f
commit 0ecb9ca
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Showing 3 changed files with 16 additions and 1 deletion.
diff --git a/packages/babel-plugin-transform-destructuring/src/index.js b/packages/babel-plugin-transform-destructuring/src/index.js
@@ -83,7 +83,11 @@ export default declare((api, options) => {
 
       if (op) {
         node = t.expressionStatement(
-          t.assignmentExpression(op, id, t.cloneNode(init)),
+          t.assignmentExpression(
+            op,
+            id,
+            t.cloneNode(init) || this.scope.buildUndefinedNode(),
+          ),
         );
       } else {
         node = t.variableDeclaration(this.kind, [

diff --git a/...in-transform-destructuring/test/fixtures/destructuring/array-unpack-optimisation/input.js b/...in-transform-destructuring/test/fixtures/destructuring/array-unpack-optimisation/input.js
@@ -11,3 +11,7 @@ var [a, b] = [...foo, bar];
 var [a, b] = [foo(), bar];
 var [a, b] = [clazz.foo(), bar];
 var [a, b] = [clazz.foo, bar];
+var [a, b] = [, 2];
+[a, b] = [1, 2];
+[a, b] = [, 2];
+; // Avoid completion record special case
diff --git a/...n-transform-destructuring/test/fixtures/destructuring/array-unpack-optimisation/output.js b/...n-transform-destructuring/test/fixtures/destructuring/array-unpack-optimisation/output.js
@@ -34,3 +34,10 @@ var _ref7 = [clazz.foo(), bar],
 var _ref8 = [clazz.foo, bar],
     a = _ref8[0],
     b = _ref8[1];
+var a,
+    b = 2;
+a = 1;
+b = 2;
+a = void 0;
+b = 2;
+; // Avoid completion record special case