Add ??= to Logical Assignment Operators (#7623)

`??=` is being merged into the Logical Assignment Operator proposal, and the overall proposal will wait until nullish coalescing is finalized.

packages/babel-plugin-proposal-logical-assignment-operators/package.json

@@ -17,6 +17,8 @@
   },
   "devDependencies": {
     "@babel/core": "7.0.0-beta.42",
-    "@babel/helper-plugin-test-runner": "7.0.0-beta.42"
+    "@babel/helper-plugin-test-runner": "7.0.0-beta.42",
+    "@babel/plugin-proposal-nullish-coalescing-operator": "7.0.0-beta.42",
+    "@babel/plugin-syntax-nullish-coalescing-operator": "7.0.0-beta.42"
   }
 }

packages/babel-plugin-proposal-logical-assignment-operators/src/index.js

@@ -12,7 +12,7 @@ export default declare(api => {
       AssignmentExpression(path) {
         const { node, scope } = path;
         const { operator, left, right } = node;
-        if (operator !== "||=" && operator !== "&&=") {
+        if (operator !== "||=" && operator !== "&&=" && operator !== "??=") {
           return;
         }
 

packages/babel-plugin-proposal-logical-assignment-operators/test/fixtures/logical-assignment/null-coalescing-without-other/input.js

@@ -0,0 +1,4 @@
+let o;
+o ??= {};
+o.a ??= 1;
+o["b"] ??= 2;

packages/babel-plugin-proposal-logical-assignment-operators/test/fixtures/logical-assignment/null-coalescing-without-other/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["proposal-logical-assignment-operators", "syntax-nullish-coalescing-operator"]
+}

packages/babel-plugin-proposal-logical-assignment-operators/test/fixtures/logical-assignment/null-coalescing-without-other/output.js

@@ -0,0 +1,6 @@
+var _o, _o2, _b;
+
+let o;
+o ?? (o = {});
+(_o = o).a ?? (_o.a = 1);
+(_o2 = o)[_b = "b"] ?? (_o2[_b] = 2);

packages/babel-plugin-proposal-logical-assignment-operators/test/fixtures/logical-assignment/null-coalescing/exec.js

@@ -0,0 +1,49 @@
+var x = undefined;
+var sets = 0;
+var obj = {
+  get x() {
+    return x;
+  },
+
+  set x(value) {
+    sets++;
+    x = value;
+  },
+};
+
+assert.equal(obj.x ??= 1, 1);
+assert.equal(sets, 1);
+assert.equal(obj.x ??= 2, 1);
+assert.equal(sets, 1);
+
+var gets = 0;
+var deep = {
+  get obj() {
+    gets++;
+    return obj;
+  },
+};
+
+obj.x = undefined;
+assert.equal(deep.obj.x ??= 1, 1);
+assert.equal(gets, 1);
+assert.equal(deep.obj.x ??= 2, 1);
+assert.equal(gets, 2);
+
+var key = 0;
+obj.x = undefined;
+assert.equal(obj[++key] ??= 1, 1);
+assert.equal(key, 1);
+key = 0;
+assert.equal(obj[++key] ??= 2, 1);
+assert.equal(key, 1);
+
+obj.x = undefined;
+key = 0;
+assert.equal(deep.obj[++key] ??= 1, 1);
+assert.equal(gets, 3);
+assert.equal(key, 1);
+key = 0;
+assert.equal(deep.obj[++key] ??= 2, 1);
+assert.equal(gets, 4);
+assert.equal(key, 1);

packages/babel-plugin-proposal-logical-assignment-operators/test/fixtures/logical-assignment/null-coalescing/input.js

@@ -0,0 +1,49 @@
+var x = undefined;
+var sets = 0;
+var obj = {
+  get x() {
+    return x;
+  },
+
+  set x(value) {
+    sets++;
+    x = value;
+  },
+};
+
+assert.equal(obj.x ??= 1, 1);
+assert.equal(sets, 1);
+assert.equal(obj.x ??= 2, 1);
+assert.equal(sets, 1);
+
+var gets = 0;
+var deep = {
+  get obj() {
+    gets++;
+    return obj;
+  },
+};
+
+obj.x = undefined;
+assert.equal(deep.obj.x ??= 1, 1);
+assert.equal(gets, 1);
+assert.equal(deep.obj.x ??= 2, 1);
+assert.equal(gets, 2);
+
+var key = 0;
+obj.x = undefined;
+assert.equal(obj[++key] ??= 1, 1);
+assert.equal(key, 1);
+key = 0;
+assert.equal(obj[++key] ??= 2, 1);
+assert.equal(key, 1);
+
+obj.x = undefined;
+key = 0;
+assert.equal(deep.obj[++key] ??= 1, 1);
+assert.equal(gets, 3);
+assert.equal(key, 1);
+key = 0;
+assert.equal(deep.obj[++key] ??= 2, 1);
+assert.equal(gets, 4);
+assert.equal(key, 1);

packages/babel-plugin-proposal-logical-assignment-operators/test/fixtures/logical-assignment/null-coalescing/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["proposal-logical-assignment-operators", "proposal-nullish-coalescing-operator"]
+}

packages/babel-plugin-proposal-logical-assignment-operators/test/fixtures/logical-assignment/null-coalescing/output.js

@@ -0,0 +1,48 @@
+var _obj$x, _obj$x2, _deep$obj, _x, _deep$obj2, _x2, _ref, _obj, _ref2, _obj2, _deep$obj3, _ref3, _ref4, _deep$obj4, _ref5, _ref6;
+
+var x = undefined;
+var sets = 0;
+var obj = {
+  get x() {
+    return x;
+  },
+
+  set x(value) {
+    sets++;
+    x = value;
+  }
+
+};
+assert.equal((_obj$x = obj.x) !== null && _obj$x !== void 0 ? _obj$x : obj.x = 1, 1);
+assert.equal(sets, 1);
+assert.equal((_obj$x2 = obj.x) !== null && _obj$x2 !== void 0 ? _obj$x2 : obj.x = 2, 1);
+assert.equal(sets, 1);
+var gets = 0;
+var deep = {
+  get obj() {
+    gets++;
+    return obj;
+  }
+
+};
+obj.x = undefined;
+assert.equal((_x = (_deep$obj = deep.obj).x) !== null && _x !== void 0 ? _x : _deep$obj.x = 1, 1);
+assert.equal(gets, 1);
+assert.equal((_x2 = (_deep$obj2 = deep.obj).x) !== null && _x2 !== void 0 ? _x2 : _deep$obj2.x = 2, 1);
+assert.equal(gets, 2);
+var key = 0;
+obj.x = undefined;
+assert.equal((_obj = obj[_ref = ++key]) !== null && _obj !== void 0 ? _obj : obj[_ref] = 1, 1);
+assert.equal(key, 1);
+key = 0;
+assert.equal((_obj2 = obj[_ref2 = ++key]) !== null && _obj2 !== void 0 ? _obj2 : obj[_ref2] = 2, 1);
+assert.equal(key, 1);
+obj.x = undefined;
+key = 0;
+assert.equal((_ref4 = (_deep$obj3 = deep.obj)[_ref3 = ++key]) !== null && _ref4 !== void 0 ? _ref4 : _deep$obj3[_ref3] = 1, 1);
+assert.equal(gets, 3);
+assert.equal(key, 1);
+key = 0;
+assert.equal((_ref6 = (_deep$obj4 = deep.obj)[_ref5 = ++key]) !== null && _ref6 !== void 0 ? _ref6 : _deep$obj4[_ref5] = 2, 1);
+assert.equal(gets, 4);
+assert.equal(key, 1);