why a = "b"; hello:a returns "b"?

Asked Sep 07 '17 at 07:47

Active Sep 07 '17 at 08:15

Viewed 68 times

I was telling to a colleage in work that [1].map(e => {attr:e}); will not do what he thinks. He was thinking that the return will be [{attr: 1}].

I though that node will crash with this code, but for my surprise, when I open the node program in the terminal, if I write that line is not crashing, is returning [undefined] in node 8. And if I write a = "b"; hello:a it returns "b".

What is happening there?

edited Sep 07 '17 at 08:15

asked Sep 07 '17 at 07:47

user2550196

5

It's a [label](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/label). – Bergi Sep 07 '17 at 07:49
2

`forEach` always returns `undefined`, to begin with. – Yury Tarabanko Sep 07 '17 at 07:51
2

`Array.foreach` return is `undefined`, you perhaps means about `Array.map`. Edit: @Yury Tarabanko exact same time :p – Orelsanpls Sep 07 '17 at 07:51
Sorry, I mean .map. An error of the question. – user2550196 Sep 07 '17 at 08:15

why a = "b"; hello:a returns "b"?

0 Answers0