PR feedback

Author: rbuckton

src/compiler/transformers/es2015.ts

@@ -3360,10 +3360,13 @@ namespace ts {
             const classStatements = visitNodes(body.statements, visitor, isStatement, 0, 1);
             const remainingStatements = visitNodes(body.statements, visitor, isStatement, 1, body.statements.length - 1);
             const varStatement = cast(firstOrUndefined(classStatements), isVariableStatement);
+
+            // We know there is only one variable declaration here as we verified this in an
+            // earlier call to isTypeScriptClassWrapper
             const variable = varStatement.declarationList.declarations[0];
             const initializer = skipOuterExpressions(variable.initializer);
 
-            // Under certain conditions, the 'ts' transformer may may introduce a class alias, which
+            // Under certain conditions, the 'ts' transformer may introduce a class alias, which
             // we see as an assignment, for example:
             //
             //  (function () {

src/compiler/transformers/ts.ts

@@ -573,6 +573,17 @@ namespace ts {
             addConstructorDecorationStatement(statements, node);
 
             if (facts & ClassFacts.UseImmediatelyInvokedFunctionExpression) {
+                // When we emit a TypeScript class down to ES5, we must wrap it in an IIFE so that the
+                // 'es2015' transformer can properly nest static initializers and decorators. The result
+                // looks something like:
+                //
+                //  var C = function () {
+                //      class C {
+                //      }
+                //      C.static_prop = 1;
+                //      return C;
+                //  }();
+                //
                 const closingBraceLocation = createTokenRange(skipTrivia(currentSourceFile.text, node.members.end), SyntaxKind.CloseBraceToken);
                 const localName = getInternalName(node);