在mongo shell中取消设置变量

Question

有没有办法在mongo shell中取消设置变量.例如,如果我myvar在定义它之前尝试引用,我会得到ReferenceError: myvar is not defined (shell):1,但是一旦我定义它并且我已经完成它,我想将它返回到该状态.

我尝试将它设置为,null并且undefined两者都不起作用.

编辑:尝试删除操作符时,我得到以下输出:

> var myvar = 5
> myvar
5
> delete myvar
false
> 
> myvar
5
> 

Answer 1

mongo shell是一个交互式JavaScript shell,因此您可以使用delete运算符:

$ mongo
MongoDB shell version: 2.2.3
connecting to: test
> myvar
Wed Feb 20 12:08:35 ReferenceError: myvar is not defined (shell):1
> myvar = {x: 1}
{ "x" : 1 }
> myvar
{ "x" : 1 }
> delete myvar
true
> myvar
Wed Feb 20 12:08:59 ReferenceError: myvar is not defined (shell):1
>