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Provide explanations for polyfills (Promise, Map, and Set).

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Ben Newman
2015-09-14 13:24:00 -04:00
committed by Sashko Stubailo
parent 3cbbf7242f
commit cf1cf7ac1f
1 changed files with 20 additions and 0 deletions
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packages/ecmascript/README.md
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@@ -243,6 +243,26 @@ Here is a list of the Babel transformers that are currently enabled:
### Polyfills
The ECMAScript 2015 standard library has grown to include new APIs and
data structures, some of which can be implemented ("polyfilled") using
JavaScript that runs in all engines and browsers today. Here are three new
constructors that are guaranteed to be available when the `ecmascript`
package is installed:
* [`Promise`](https://github.com/meteor/promise)<br>
A `Promise` allows its owner to wait for a value that might not be
available yet. See [this tutorial](https://www.promisejs.org/) for more
details about the API and motivation. The Meteor `Promise`
implementation is especially useful because it runs all callback
functions in recycled `Fiber`s, so you can use any Meteor API, including
those that yield (e.g. `HTTP.get`, `Meteor.call`, or `MongoCollection`),
and you never have to call `Meteor.bindEnvironment`.
* [`Map`](https://github.com/zloirock/core-js#map)<br>
An associative key-value data structure where the keys can be any
JavaScript value (not just strings). Lookup and insertion take constant
time.
* [`Set`](https://github.com/zloirock/core-js#set)<br>
A collection of unique JavaScript values of any type. Lookup and
insertion take constant time.