Support differences of spread operator with spec

[iamdustan]

This bit of code works perfectly fine with Traceur.

var $$ = (selector, context=document) => [...context.querySelectorAll(selector)];

With the es6-transpiler the output is:

var $$ = function(selector)  {function ITER$0(v,f){var $Symbol_iterator=typeof Symbol!=='undefined'&&Symbol.iterator||'@@iterator';if(v){if(Array.isArray(v))return f?v.slice():v;var i,r;if(typeof v==='object'&&typeof (f=v[$Symbol_iterator])==='function'){i=f.call(v);r=[];while((f=i['next']()),f['done']!==true)r.push(f['value']);return r;}}throw new Error(v+' is not iterable')};var context = arguments[1];if(context === void 0)context = document;
      return [].concat(ITER$0((context).querySelectorAll(selector)));
    };

and the following error is thrown:

Uncaught Error: [object NodeList] is not iterable.

Is this expected and part of the not-yet-supported iterator-able pieces?

[termi]

This problem is on specification side. In current version of spec spread operation is only allowed on Array or on objects with Iterator protocol implementation. It doesn't allow on array-like objects like {0: 'first', length: 1} I am fired a bug about this problem https://bugs.ecmascript.org/show_bug.cgi?id=2034 (invalid)

btw, the current version of traceur does not support this: http://google.github.io/traceur-compiler/demo/repl.html#debugger%3B%0A%0Avar%20a%20%3D%20%5B...document.querySelectorAll('div')%5D throw a error: TypeError: Cannot spread non-iterable object.

Update: i am sorry this link is invalid, I can't find a valid link right now

[termi]

The easiest way for you is to implement Iterator Protocol on NodeList. Something like this:

var $Symbol_iterator=typeof Symbol!=='undefined'&&Symbol.iterator||'@@iterator';
NodeList[$Symbol] = function() {
  return {
    next: function() {//do it
    }
  }
}

[iamdustan]

Ah. That worked in a previous version of traceur.

Using the following syntax works in Firefox Nightly 33, but not in es6-transpiler or traceur.

var els = document.querySelectorAll('*');
var arr = [for (_ of els) _];
console.log(arr); // => []<Node>’s

[iamdustan]

Also, is the '@@iterator' name still spec or has it changed to some private Symbol or something thereabouts. Is this level of implementation detail a concern or goal of es6-transpiler? Thanks @termi.

[termi]

@iamdustan The goal of es6-transpiler is to support Symbol.iterator. The '@@iterator' is just a fallback