From 8ea87ed68d59c71ee21e08dd44d007cf1147918a Mon Sep 17 00:00:00 2001 From: Website Deployment Script Date: Wed, 25 May 2016 20:23:15 +0000 Subject: [PATCH] Updated docs for next --- releases/next/docs/javascript-environment.html | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/releases/next/docs/javascript-environment.html b/releases/next/docs/javascript-environment.html index b12011e89a1..527fca4a8c7 100644 --- a/releases/next/docs/javascript-environment.html +++ b/releases/next/docs/javascript-environment.html @@ -1,4 +1,4 @@ -JavaScript Environment – React Native | A framework for building native apps using React
React Nativenext

Quick Start

Tutorials

Sample Applications

Community Resources

Guides

Guides (iOS)

Guides (Android)

components

apis

Polyfills

JavaScript Environment #

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JavaScript Runtime #

When using React Native, you're going to be running your JavaScript code in two environments:

  • On iOS simulators and devices, Android emulators and devices React Native uses JavaScriptCore which is the JavaScript engine that powers Safari. On iOS JSC doesn't use JIT due to the absence of writable executable memory in iOS apps.
  • When using Chrome debugging, it runs all the JavaScript code within Chrome itself and communicates with native code via WebSocket. So you are using V8.

While both environments are very similar, you may end up hitting some inconsistencies. We're likely going to experiment with other JS engines in the future, so it's best to avoid relying on specifics of any runtime.

JavaScript Syntax Transformers #

Syntax transformers make writing code more enjoyable by allowing you to use new JavaScript syntax without having to wait for support on all interpreters.

As of version 0.5.0, React Native ships with the Babel JavaScript compiler. Check Babel documentation on its supported transformations for more details.

Here's a full list of React Native's enabled transformations.

ES5

  • Reserved Words: promise.catch(function() { });

ES6

ES7

Specific

  • JSX: <View style={{color: 'red'}} />
  • Flow: function foo(x: ?number): string {}

Polyfills #

Many standards functions are also available on all the supported JavaScript runtimes.

Browser

ES6

ES7

Specific

  • __DEV__
Next →

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© 2016 Facebook Inc.
React Nativenext

Quick Start

Tutorials

Sample Applications

Community Resources

Guides

Guides (iOS)

Guides (Android)

components

apis

Polyfills

JavaScript Environment #

Edit on GitHub

JavaScript Runtime #

When using React Native, you're going to be running your JavaScript code in two environments:

  • On iOS simulators and devices, Android emulators and devices React Native uses JavaScriptCore which is the JavaScript engine that powers Safari. On iOS JSC doesn't use JIT due to the absence of writable executable memory in iOS apps.
  • When using Chrome debugging, it runs all the JavaScript code within Chrome itself and communicates with native code via WebSocket. So you are using V8.

While both environments are very similar, you may end up hitting some inconsistencies. We're likely going to experiment with other JS engines in the future, so it's best to avoid relying on specifics of any runtime.

JavaScript Syntax Transformers #

Syntax transformers make writing code more enjoyable by allowing you to use new JavaScript syntax without having to wait for support on all interpreters.

As of version 0.5.0, React Native ships with the Babel JavaScript compiler. Check Babel documentation on its supported transformations for more details.

Here's a full list of React Native's enabled transformations.

ES5

  • Reserved Words: promise.catch(function() { });

ES6

ES7

Specific

  • JSX: <View style={{color: 'red'}} />
  • Flow: function foo(x: ?number): string {}

Polyfills #

Many standards functions are also available on all the supported JavaScript runtimes.

Browser

ES6

ES7

Specific

  • __DEV__
Next →

We are planning improvements to the React Native documentation. Your responses to this short survey will go a long way in helping us provide valuable content. Thank you!

Take Survey
© 2016 Facebook Inc.