字符串枚举的反向映射 [英] Reverse-Mapping for String Enums
本文介绍了字符串枚举的反向映射的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我想在打字稿中使用字符串枚举,但在其中看不到对反向映射的支持. 我有一个这样的枚举:
I wanted to use string enums in typescript but I can't see a support for reversed mapping in it. I have an enum like this:
enum Mode {
Silent = "Silent",
Normal = "Normal",
Deleted = "Deleted"
}
我需要这样使用它:
let modeStr: string;
let mode: Mode = Mode[modeStr];
是的,我不知道它在modeStr
字符串中是什么,并且我需要将其解析为枚举,或者如果在枚举定义中未显示该字符串,则会在运行时解析失败.
我该如何做到整洁呢?
预先感谢
and yes I don't know what is it there in modeStr
string and I need it parsed to the enum or a fail at parsing in runtime if the string is not presented in the enum definition.
How can I do that as neat as it can be?
thanks in advance
推荐答案
我们可以将Mode
设置为类型,并将值设置为相同的类型.
We can make the Mode
to be a type and a value at the same type.
type Mode = string;
let Mode = {
Silent: "Silent",
Normal: "Normal",
Deleted: "Deleted"
}
let modeStr: string = "Silent";
let mode: Mode;
mode = Mode[modeStr]; // Silent
mode = Mode.Normal; // Normal
mode = "Deleted"; // Deleted
mode = Mode["unknown"]; // undefined
mode = "invalid"; // "invalid"
更严格的版本:
type Mode = "Silent" | "Normal" | "Deleted";
const Mode = {
get Silent(): Mode { return "Silent"; },
get Normal(): Mode { return "Normal"; },
get Deleted(): Mode { return "Deleted"; }
}
let modeStr: string = "Silent";
let mode: Mode;
mode = Mode[modeStr]; // Silent
mode = Mode.Normal; // Normal
mode = "Deleted"; // Deleted
mode = Mode["unknown"]; // undefined
//mode = "invalid"; // Error
字符串枚举为此答案:
enum Mode {
Silent = <any>"Silent",
Normal = <any>"Normal",
Deleted = <any>"Deleted"
}
let modeStr: string = "Silent";
let mode: Mode;
mode = Mode[modeStr]; // Silent
mode = Mode.Normal; // Normal
//mode = "Deleted"; // Error
mode = Mode["unknown"]; // undefined
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