javascript - 如何修复 Node 终端中的 'variable is not defined' 以及为什么会发生这种情况？

Question

这个问题已经有答案了:

Is there any difference between declared and defined variable (1 个回答)

已关闭 4 年前。

我定义了一个变量并为其分配了一个有语法错误的函数。它抛出错误。现在，我无法将该变量用于任何用途，它总是显示“抛出:”ReferenceError:变量未定义'

> let bg = 'asasas-123d'
undefined
> let fd = bg.substring(indexOf('-')+1)
Thrown:
ReferenceError: indexOf is not defined
> let fd = bg.substring(bg.indexOf('-')+1)
Thrown:
SyntaxError: Identifier 'fd' has already been declared
>  fd = bg.substring(bg.indexOf('-')+1)
Thrown:
ReferenceError: fd is not defined
> let  fd = bg.substring(bg.indexOf('-')+1)
Thrown:
SyntaxError: Identifier 'fd' has already been declared
> fd = bg.substring(bg.indexOf('-')+1)
Thrown:
ReferenceError: fd is not defined
> fd
Thrown:
ReferenceError: fd is not defined
> console.log(fd);
Thrown:
ReferenceError: fd is not defined

Answer 1

只需重新启动终端并运行以下命令:

> let bg = 'asasas-123d'
> let fd = bg.substring(bg.indexOf("-") + 1))