在TypeScript中，如何将布尔值转换为数字，如0或1 [英] In TypeScript, How to cast boolean to number, like 0 or 1

问题描述

我们知道，类型转换在TypeScript中称为断言类型。以下代码部分：

As we know, the type cast is called assertion type in TypeScript. And the following code section:

// the variable will change to true at onetime
let isPlay: boolean = false;
let actions: string[] = ['stop', 'play'];
let action: string = actions[<number> isPlay];

编译时出错

Error:(56, 35) TS2352: Neither type 'boolean' nor type 'number' is assignable to the other.

然后我尝试使用任何类型：

let action: string = actions[<number> <any> isPlay];

也出错了。我怎样才能重写这些代码。

Also go wrong. How can I rewrite those code.

推荐答案

你不能只是强制转换它，问题是在运行时不仅在编译时。

You can't just cast it, the problem is at runtime not only at compile time.

你有几种方法可以做到这一点：

You have a few ways of doing that:

let action: string = actions[isPlay ? 1 : 0];
let action: string = actions[+isPlay];
let action: string = actions[Number(isPlay)];

编译器和运行时都应该没问题。

Those should be fine with both the compiler and in runtime.

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