Use Object.assign or Spread Operator in React/Redux? Which is a better practise

Question

I have some confusion about using Object.assign for React and Redux.

I read this article.

It says ES6 Does not supported by all browsers but I

Answer 1

Ok may be I was not really right but this is from Dan Abramov (redux creator)

Finally, you need to remember that Object.assign is a new method in ES6, so it is not natively available in all the browsers. You should use a polyfill, either the one that ships with Babel or a standalone Object.assign polyfill, to use it without risking crashing your website.

Another option that doesn't require a polyfill is to use the new object spread operator, which is not part of ES6. However, it is proposed for ES7. It is fairly popular, and it is enabled in Babel if you use the stage two preset.