Destructuring and default parameters in functions

Allen Wirfs-Brock allen at wirfs-brock.com
Thu Jun 27 09:07:04 PDT 2013


On Jun 27, 2013, at 3:19 AM, Marius Gundersen wrote:

> I'm testing some code in the latest version of Firefox, and it seems I'm not able to define default values to function arguments which are destructured. For example:
> 
> function test([a, b] = [1, 2]){
> 
> 
>     return a+b;
> }
> 
> 
> test([3, 4])//expect 7
> test([3])//expect NaN
> test()//expect 3
> 
> //Exception: missing ) after formal parameters (line 1)
> 
> I haven't found this defined in the current grammar,

see http://people.mozilla.org/~jorendorff/es6-draft.html#sec-13 
 FormalParameter :
      BindingElement

http://people.mozilla.org/~jorendorff/es6-draft.html#sec-12.2.4 
  BindingElement :
      BindingPattern Initialiser<opt>

  BindingPattern :
     ArrayBindingPattern
   

> but would be useful for something I'm currently working on. Or maybe it just isn't implemented in Firefox?

> 
> Marius Gundersen
> 
> 
> _______________________________________________
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