流，类型非结构化对象

Question

我找不到语法来输入这种非结构化对象

const { height: deviceHeight, width: deviceWidth } = Dimensions.get("window");

现在deviceHeight和deviceWidth都被发现了，都应该是数字。

Answer 1

我想你想要的是：

const { height: deviceHeight, width: deviceWidth }: { height: number, width: number } = Dimensions.get("window");

您可以看到，通过将其插入如下所示的内容中，可以正确地键入deviceHeight和deviceWidth：

// @flow
const { height: deviceHeight, width: deviceWidth }: { height: number, width: number } = { height: 1, width: 2 };

function logString(str: string) {
  console.log(str);
}

logString(deviceHeight);

...which给出以下输出：

logString(deviceHeight);
          ^ Cannot call `logString` with `deviceHeight` bound to `str` because number [1] is incompatible with string [2].

(See it on flow.org)