字符串枚举的反向映射

Question

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：

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modeStr字符串中有什么，如果字符串未在枚举定义中显示，我需要将其解析为枚举或在运行时解析失败。我该如何做到整洁呢？提前致谢

Answer 1

我们可以将其Mode设为一个类型，并将值设为同一类型。

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

字符串枚举作为此答案：

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