浏览器是否在内部将 ES6 转换为 ES5？

Question

Since modern browsers support ES6. Do they internally transpiles ES6 down to ES5, and then execute the code? Or they can understand ES6 code natively using C++ engine?

If they can run ES6 directly, how does it ensure the behaviour of executing ES6 code is absolutely equivalent to executing the transpiled ES5 version of that code?

Answer 1

The answer to your question is simple: No, browser doesn't transpile your code.

There is no need because new specification try to stay backward compatible by adding new syntactic sugar, new functions and new apis, keeping the existing stuff as is.