Map on Safari throws error when constructor is passed arguments

[benhughes]

After compiling the following with Traceur (using es6ify):

var some var = new Map([
      ['key', 'data']
])

Safari throws

[Error] TypeError: Map constructor does not accept arguments

I see from http://kangax.github.io/compat-table/es6/ that Safari does not support this feature of ES6. Are there any plans to polyfill it in Safari?

Traceur version: 0.0.79
Safari version: 8.0.2

[arv]

We have a polyfill, so it is just a matter of changing the detection.

[paulftw]

+1
This breaks Angular 2.0 in Safari

[paulftw]

As a workaround I modified polyfillMap(...) in src/runtime/polyfills/Map.js - added the following snippet:

  if (!global.Map) {
    global.Map = Map;
  } else {
    try {
      new global.Map([['k', 'v']]);
    } catch (e) {
      // Native Map doesn't support constructor arguments (Safari 8 and below).
      global.Map = Map;
    }
  }

[hydrotik]

+1 Angular 2.0 broken on Safari

[caitp]

it works in WebKit Nightly though, or did last I checked =) Just be sure to use WK Nightly during your demos ;)

[arv]

I want to fix this... I just haven't had enough time to get it fixed.

1. If the browser has no Symbol support use polyfill.
2. If the browser has no Symbol.iterator support use polyfill.
3. If new Set([1]).size !== 1 use polyfill.

Patches welcome.

[zloirock]

@arv paulmillr/es6-shim#326 (comment)

[arv]

@zloirock I don't agree with that list. iterator closing is an abomination. I wish I had been stronger in opposing it at TC39. It requires all your code to be wrapped in a try/catch which is insane.

[zloirock]

@arv abomination, but required for compliance with the specification. Wrapper for constructor much better complete replacement of collection.

[arv]

@zloirock No doubt. We just have to prioritize things based on importance and this one is very low.

[paulftw]

@arv I've posted a workaround earlier, if you are too busy - I don't mind spending some time on a mature pull request.

Only problem is I have no idea what is considered an acceptable PR for traceur.

Could you point out a similar patch to use as scaffolding? Something small that's been accepted recently, addresses a similar feature, has tests, etc.
I'm aware of CONTRIBUTING.md.

BTW I'm not sure your test #3 will work though - Map constructor seems to throw an exception if any params are present.

[arv]

Yeah 3 needs a try/catch.

This commit might be serve as inspiration: 1951203

Here is where the setup is done: https://github.com/google/traceur-compiler/blob/master/src/runtime/polyfills/Map.js#L195-L209 and similarly for Set.

We might also need to have a way to detect if native Symbols are supported: https://github.com/google/traceur-compiler/blob/master/src/runtime/runtime.js#L462-L473