Is the following valid ECMAScript 6? It seems to be supported by the latest version of Babel but it isn’t by TypeScript. I couldn’t find any ES6 references dealing with this case. Answer No, this is not valid ECMAScript 6. ES6 does only support rest syntax in function parameters and array destructuring, and spread syntax in function calls and array construction. It seems to be supported by the latest version of Babel Babel does implement the objectRestSpread ES7 proposal as a experimental plugin. You shouldn’t use this feature, it may break at any time.