add basic support for class property initializers - #619

lib/6to5/transformation/transformers/es6/classes.js

@@ -167,6 +167,8 @@ ClassTransformer.prototype.buildBody = function () {
     } else if (t.isPrivateDeclaration(node)) {
       this.closure = true;
       body.unshift(node);
+    } else if (t.isClassProperty(node)) {
+      this.pushProperty(node);
     }
   }
 
@@ -245,6 +247,28 @@ ClassTransformer.prototype.pushMethod = function (node) {
   defineMap.push(mutatorMap, methodName, "enumerable", node.computed, false);
 };
 
+/**
+ * Description
+ *
+ * @param {Node} node
+ */
+
+ClassTransformer.prototype.pushProperty = function (node) {
+  if (!node.value) return;
+
+  if (node.static) {
+    var key = t.memberExpression(this.className, node.key);
+    this.body.push(
+      t.expressionStatement(t.assignmentExpression("=", key, node.value))
+    );
+  } else {
+    var key = t.memberExpression(t.thisExpression(), node.key);
+    this.constructor.body.body.unshift(
+      t.expressionStatement(t.assignmentExpression("=", key, node.value))
+    );
+  }
+};
+
 /**
  * Replace the constructor body of our class.
  *

lib/6to5/types/builder-keys.json

@@ -99,6 +99,7 @@
     "key": null,
     "value": null,
     "computed": false,
+    "static": false,
     "kind": null
   },
 

lib/6to5/types/visitor-keys.json

@@ -73,7 +73,7 @@
   "AnyTypeAnnotation":           [],
   "ArrayTypeAnnotation":         [],
   "BooleanTypeAnnotation":       [],
-  "ClassProperty":               ["key"],
+  "ClassProperty":               ["key", "value"],
   "DeclareClass":                [],
   "DeclareFunction":             [],
   "DeclareModule":               [],

package.json

@@ -33,7 +33,7 @@
     "test": "make test"
   },
   "dependencies": {
-    "acorn-6to5": "0.11.1-28",
+    "acorn-6to5": "0.11.1-29",
     "ast-types": "~0.6.1",
     "chalk": "^0.5.1",
     "chokidar": "0.12.6",

test/fixtures/transformation/es6-classes-playground-property-initializers/instance/exec.js

@@ -0,0 +1,7 @@
+class MyClass {
+  myProp = { someValue: 42 };
+}
+
+var myClass = new MyClass;
+assert.ok(myClass.myProp !== MyClass.prototype.myProp);
+assert.equal(myClass.myProp.someValue, 42);

test/fixtures/transformation/es6-classes-playground-property-initializers/options.json

@@ -0,0 +1,3 @@
+{
+  "playground": true
+}

test/fixtures/transformation/es6-classes-playground-property-initializers/static/exec.js

@@ -0,0 +1,5 @@
+class MyClass {
+  static myProp = { someValue: 42 };
+}
+
+assert.equal(MyClass.myProp.someValue, 42);