为什么我可以在浏览器控制台（比如Chrome）中重新定义一个变量，而不能在我的笔记本电脑（Mac）上的终端控制台（节点）中重新定义。

终端节点控制台:

> let varA = varB;
< Uncaught ReferenceError: varB is not defined
> let varB = "bla";
> let varA = varB;
< Uncaught SyntaxError: Identifier 'varA' has already been declared
> varA
< Uncaught ReferenceError: varA is not defined


//dropping let
> varA = varB;
< Uncaught ReferenceError: Cannot access 'varA' before initialization

Chrome控制台:

> let varA = varB;
< VM510:1 Uncaught ReferenceError: varB is not defined
    at <anonymous>:1:12
(anonymous) @ VM510:1
> let varB = "bla";
< undefined
> let varA = varB;
< undefined
> varA
< "bla"