ES6 / 2015中的无安全属性访问（和有条件分配） [英] Null-safe property access (and conditional assignment) in ES6/2015

问题描述

在ES6（ES2015 / JavaScript.next / Harmony）中有 null -safe属性访问（空传播/存在）运算符，如 <$ c $例如， CoffeeScript 中的c>？。 还是计划用于ES7？

Is there a null-safe property access (null propagation / existence) operator in ES6 (ES2015/JavaScript.next/Harmony) like ?. in CoffeeScript for example? Or is it planned for ES7?

var aThing = getSomething()
...
aThing = possiblyNull?.thing

这将大致如下：

if (possiblyNull != null) aThing = possiblyNull.thing

理想情况下，如果 possibleNull，则解决方案不应该分配（甚至 undefined ）到 aThing 是 null

Ideally the solution should not assign (even undefined) to aThing if possiblyNull is null

推荐答案

目前处于第1阶段的完成：无效传播。

A feature that accomplishes that is currently in stage 1: Null Propagation.

https://github.com/tc39/proposals

您可以在这里查看：

https://github.com/claudepache/es-optional-chaining
https://docs.google.com/presentation/d/11O_wIBBbZgE1bMVRJI8kGnmC6dWCBOwutbN9SWOK0fU/view

如果你想使用它今天，有一个Babel插件来实现。

If you want to use it today, there is a Babel plugin that accomplishes that.

https://github.com/davidyaha/ecmascript-optionals-proposal

更新（2017 -08-01）：如果要使用官方插件，您可以尝试使用新变换的Babel 7的Alpha版本。您的里程可能会有所不同

Update (2017-08-01): If you want to use an official plugin, you can try the alpha build of Babel 7 with the new transform. Your mileage may vary

https://www.npmjs.com/package/babel-plugin-transform-optional-chaining

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