Array.slice on array with one element

Question

I'm really confused by this. If I do something like this:
[1].slice(1)
it returns an empty array (in the chrome interactive console). But if I compare:
[1].slice(1) === []
it's always false. So my Question is, what does [1].slice(1) really return?

What are you trying to do? There is nothing to slice at index 1 — Esailija
– Esailija, Commented Aug 13, 2012 at 16:52
writing a lispy to javascript compiler and trying to translate (rest '(1)). — rabra
– rabra, Commented Aug 13, 2012 at 16:58

SLaks · Accepted Answer · 2012-08-13 16:52:17Z

8

=== compares objects by references.
You're comparing two different array objects which are both empty.

If you want to check whether an array is empty, check whether .length === 0.

answered Aug 13, 2012 at 16:52

SLaks

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Comments

Oriol · Accepted Answer · 2012-08-13 17:01:44Z

1

That's not a problem of slice or ===.

If you do [1]==[1], it returns false.

That's because both == and === compare objects by reference

answered Aug 13, 2012 at 17:01

Oriol

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Comments

Nick · Accepted Answer · 2012-08-13 16:50:32Z

-1

[] === [] also returns false. [1].slice(1) does in fact return []

answered Aug 13, 2012 at 16:50

Nick

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Comments

David Hellsing · Accepted Answer · 2012-08-13 16:52:47Z

-1

You better check the length:

[1].slice(1).length; // falsey

answered Aug 13, 2012 at 16:52

David Hellsing

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