从未定义中解构时避免错误 [英] Avoid an error when destructuring from undefined

问题描述

让我说我有这段代码:

const {x, y} = point;

Babel会将其转换为:

Babel will turn this into:

var _point = point,
    x = _point.x,
    y = _point.y;

哪个很好，但是如果未定义点怎么办?现在我得到一个错误:

Which is fine, but what if point is undefined? Now I get an error:

"Cannot read property 'x' of undefined".

那我该如何避免呢?

我想做类似的事情

const {x, y} = {} = point;

但这是语法错误.

我只能看到这是一个选择:

I can only see that this is an option:

const {x, y} = point || {};

哪个通天塔转移到:

var _ref = point || {},
    x = _ref.x,
    y = _ref.y;

在这里，我们正在创建一个对象只是为了避免发生未定义的错误.这似乎很浪费.

Here we're creating an object just to avoid an undefined error. This seems wasteful.

我缺少一些语法可以避免这种情况吗?会变成这样的东西:

Is there some syntax I'm missing that would avoid this? Something that would transpile to something like this:

var x, y;
if (typeof point !== 'undefined') {
    x = point.x;
    y = point.y;
}

推荐答案

要处理ES6对象解构中的未定义错误，您可以执行以下操作

To handle undefined error in ES6 object destructuring, you can do something like following

const {x, y} = {...point};
console.log(x)      // undefined                  
console.log(y)      // undefined                  

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