Raynos/a.md

## a.md

      
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              a.md
            
          
    ES6 what can be shimmed and what not.

Currently only lists things that can be shimmed or are experimentally implemented
Note that for any kind of decent ES6 support we need an ES6 transpiler. A few projects are attempting this Reference SO question

traceur
Caja
ES transpiler


## browsers.md

      
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              browsers.md
            
          
    Firefox


WeakMaps, Maps and Sets
Old proxies (not direct proxies)
let, const

Chrome (requires harmony flags on)


let, const
WeakMaps, Maps and Sets
old proxies.


## shimmable.md

      
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              shimmable.md
            
          
    Shimmables of ES6

The following are currently shimmed. Note a lot of these are not natively implemented anywhere yet.
String extras

By ES6-shim

String.prototype.repeat
String.prototype.startsWith
String.prototype.endsWith
String.prototype.contains

Array extras

By ES6-shim]1

Array.from
Array.of

Number extras

By ES6-shim

Number.isFinite
Number.isNaN
Number.toInteger
Number.isInteger

Object extras

By ES6-shim

Object.getOwnPropertyDescriptors
Object.getPropertyDescriptor
Object.getPropertyNames
Object.is
Object.isnt

Math extras

By ES6-shim

Math.sign

By fdlibm

Math.log10
Math.log1p
Math.expm1
Math.cosh
Math.sinh
Math.tanh
Math.acosh
Math.asinh
Math.atanh
Math.hypot
Math.trunc
Math.sign

By rwldrn

Math.cbrt

Maps, Sets and WeakMaps

ES6-shim covers Map and Set. WeakMap shim. ES6 collections also has alternative shims with special note on Andrea's WeakMap implementation choice.

  
## unshimmable.md

      
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              unshimmable.md
            
          
    Unshimmable subset of ES6

These cannot be shimmed currently.
Any new syntax

Can not be shimmed. This includes

let
const
typeof null === "null"

Proxies

I've not seen any implementation. It's nearly impossible to emulate without severe restrictions. Note it's possible to emulate the newer specification of proxies from the older specification (firefox/chrome have the older implementation lying around)
Modules

module syntax cannot be shimmed. Depending on what the programmatic module API is like it may be possible to shim but it's not finalized.