是否可以将数量限制在某个范围内 [英] Is it possible to restrict number to a certain range

问题描述

从 typescript 2.0 RC(甚至是 beta 版?)开始，可以使用数字文字类型，如 type t = 1 |2;.是否可以将类型限制为数字范围，例如0-255，没有在类型中写出256个数字?

Since typescript 2.0 RC (or even beta?) it is possible to use number literal types, as in type t = 1 | 2;. Is it possible to restrict a type to a number range, e.g. 0-255, without writing out 256 numbers in the type?

就我而言，库接受调色板的颜色值从 0 到 255，我更愿意只列举几个但将其限制为 0-255:

In my case, a library accepts color values for a palette from 0-255, and I'd prefer to only name a few but restrict it to 0-255:

const enum paletteColor {
  someColor = 25,
  someOtherColor = 133
}
declare function libraryFunc(color: paletteColor | 0-255); //would need to use 0|1|2|...

推荐答案

不，这不可能.打字稿中没有这种精确的类型约束(还没有?)

No it's not possible. That kind of precise type constraint is not available in typescript (yet?)

只有运行时检查/断言才能做到这一点:(

Only runtime checks/assertions can achieve that :(

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