TypeScript 字符类型？
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TypeScript character type?
提问by charliebrownie
My question is very brief. I am new to TypeScript, been searching around here and there but didn't find yet an answer.
我的问题很简短。我是 TypeScript 的新手，一直在四处寻找，但还没有找到答案。
Does any experienced TypeScripter know if there is a character Type or an easy way to achieve one?
有没有经验丰富的 TypeScripter 知道是否有字符 Type 或实现一个的简单方法？
采纳答案by Ryan Cavanaugh
TypeScript does not have a type for representing fixed-length strings.
TypeScript 没有用于表示固定长度字符串的类型。
回答by rossipedia
I'm not sure about easy, but you could sorta do something with string literal types:
我不确定easy，但你可以用字符串文字类型做一些事情：
type Char = 'a' | 'b' | 'c' | 'd' | 'e' | 'f' | 'g' | 'h' | 'i' | 'j' | 'k'
| 'l' | 'm' | 'n' | 'o' | 'p' | 'q' | 'r' | 's' | 't' | 'u' | 'v' | 'w' | 'x'
| 'y' | 'z' | 'A' | 'B' | 'C' | 'D' | 'E' | 'F' | 'G' | 'H' | 'I' | 'J' | 'K'
| 'L' | 'M' | 'N' | 'O' | 'P' | 'Q' | 'R' | 'S' | 'T' | 'U' | 'V' | 'W' | 'X'
| 'Y' | 'Z' | '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' // etc....;
of course, this is a fairly brittle solution and breaks down when you consider unicode characters, and I wouldn't really suggest it. As Ryan mentions, JavaScript itself doesn't have any notion of a fixed length string, nor the concept of a charas distinct from a string.
当然，这是一个相当脆弱的解决方案，当您考虑 unicode 字符时会崩溃，我真的不建议这样做。正如 Ryan 提到的，JavaScript 本身没有任何固定长度字符串的概念，也没有char区别于 a的概念string。
回答by cocoseis
A Char is simply a number. Since the basic types of TypeScript do not include Chars what you could do is store a number and convert it back and forth:
Char 只是一个数字。由于 TypeScript 的基本类型不包括 Chars，您可以做的是存储一个数字并将其来回转换：
var number = "h".charCodeAt(0);
var char = String.fromCharCode(number)
And to something like:
和类似的东西：
class Char {
private _value:Number;
constructor(char: Number | String){
this.setValue(char);
}
get getValue():String {
return String.fromCharCode(this._value);
}
set setValue(char: Number | String) {
if (typeof char === "number") {
this._value = char;
}
else {
this._value = char.charCodeAt(0);
}
}
}
回答by Andreas
You could use a regex within TypeGuard to contain it's type eg:(you can declare an empty enum to get a new type to be associated with the type guard)
您可以在 TypeGuard 中使用正则表达式来包含它的类型，例如:(您可以声明一个空枚举以获得与类型保护关联的新类型）
enum CharType { }
export type Char = string & CharType
const isChar=(str: string): str is Char => /^(.|\n)$/.test(
str
)
export char(c:string):Char{
//you can also use is char here for to test whether actually is char
if (!isChar(c)){
throw new Error('not a char')
}
return c
}
Now Char matches only things that come from calling char(eg actually casted by calling the function rather than just asserted on build time. The compiler simply accepts that a Char is returned and that's actually true if you think of it since it will just throw otherwise)
现在 Char 只匹配来自调用 char 的东西（例如，实际上是通过调用函数而不是在构建时断言。编译器简单地接受返回一个 Char，如果你想到它，这实际上是正确的，因为它只会抛出否则)
Original Source(applied to date string): Atomic Object
原始来源（应用于日期字符串）： 原子对象
Assumptions: I assume that by mentioning typescript you mean a type used for compile-time checks by typescript compiler and not looking for any kind of optimization on the actual compiled js side(since js only has strings)
假设：我假设提到 typescript 是指 typescript 编译器用于编译时检查的类型，而不是在实际编译的 js 端寻找任何类型的优化（因为 js 只有字符串）
The only issue I can see is that you can pass whatever to char function and it will only throw at run time. But you will never reach to a state where you expect a Char and you get something else(since Chars only come from calling char).
我能看到的唯一问题是您可以将任何内容传递给 char 函数，它只会在运行时抛出。但是你永远不会达到你期望一个 Char 而你得到其他东西的状态（因为 Chars 只来自调用 char）。
On a side note even java casts throw just runtime exceptions.
附带说明一下，即使 java 强制转换也只抛出运行时异常。
Although the above approach might not have much to do with casts, I do find some commonalities...
虽然上述方法可能与演员没有太大关系，但我确实发现了一些共同点......
回答by zhangjinzhou
As I know, the basic types of typescript don't include char.
据我所知，打字稿的基本类型不包括字符。
