Why is "_" undefined while "x" is a reference error in javascript?

Question

When I enter _ into a nodejs terminal, I get "undefined", but when I type in x, I get a reference error. I thought underscores were just another character, why am I getting different results?

$ nodejs
> _
undefined
> x
ReferenceError: x is not defined
>

I thought both would give me a reference error.

It *is* just another identifier, so it must exist in scope: question is then only why, and what purpose. — user2864740, Sep 09 '19 at 04:54
@NicolásAlarcónRapela that doesn't seem applicable to this question — Phil, Sep 09 '19 at 04:55
Not a duplicate of the “other” linked above. Op is questioning why one (arbitrary) identifier is not defined, while _ another (seemingly arbitrary) identifier is. — user2864740, Sep 09 '19 at 04:55
The posted one involving arbitrary code that happens to contain “x”. — user2864740, Sep 09 '19 at 05:01

score 3 · Accepted Answer · answered Sep 09 '19 at 04:54

3

In node.js, _ would return last expression's result.

If you try to using _ as first command, it will return undefined.

answered Sep 09 '19 at 04:54

lsv

756
4
14

Why is "_" undefined while "x" is a reference error in javascript?

1 Answers1