Are patterns in parameter declarations irrefutable? In other words, given:
function foo({ opt1 }) { return opt1 }
What happens if we call foo()?
1. An exception is thrown
2. undefined is returned
I’d expect (2). If opt1 had a default value, I’d expect that value to be
returned.
What happens if we call foo({})?
1. An exception is thrown
2. undefined is returned
I’m asking, because I’ve seen the pattern
function foo({ opt1 = 3 } = {}) { return opt1 }
If explicitly marking something as irrefutable is necessary, I’d prefer:
function foo({ opt1 = 3 }?) { return opt1 }
It’s a bit of a shame that destructuring and parameter declarations diverge,
but I guess it can’t be helped.
Axel
--
Dr. Axel Rauschmayer
a...@rauschma.de
home: rauschma.de
twitter: twitter.com/rauschma
blog: 2ality.com
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