Question

我正在使用带有目标ES5的TypeScript 2.2.1

我有几个枚举如下

enum PermissionLevel {
    ACCOUNT_OWN,
    ACCOUNT_OTHER,
    USER_OWN
}

enum Permission {
    ACCOUNT_CREATE,
    USER_CREATE
}

我有一个输入JSON，如下所示

{
    "ACCOUNT_OWN": [
        "USER_CREATE",
        "ACCOUNT_CREATE"
    ],
    "ACCOUNT_OTHER": [
        "USER_CREATE"
    ]
}

我想将此输入存储为Map<Permission, Array<PermissionLevel>>

以下是我的代码

        // assume authJson is the input and is a valid JSON.
        this.userPermissions = new Map<Permission, Array<PermissionLevel>>();
        for (let [level, permissions] of Object.entries(authJson)) {
            let newLevel: PermissionLevel = <any>PermissionLevel[level];
            for (let perm of permissions) {
                let newPermission: Permission = <any>Permission[perm];
                if (this.userPermissions.get(newPermission)) {
                    this.userPermissions.set(newPermission, this.userPermissions.get(newPermission).concat(newLevel));
                } else {
                    this.userPermissions.set(newPermission, new Array<PermissionLevel>().concat(newLevel));
                }
            }
        }

        console.log(JSON.stringify(this.userPermissions));

最后一个语句的输出是空的:(。不知道我在这里做错了什么。

更新：我刚发现下面有运行时错误

EXCEPTION: Uncaught (in promise): ReferenceError: PermissionLevel is not defined

这是一个TS小提琴 - https://jsfiddle.net/hrwyc6zv/1/

Answer 1

javascript中的地图对象不是JSON。因此，JSON.stringify不会显示其实际内容。

Firefox中的小测试：

var x = new Map()
x.set('a','b')
-> Map { a: "b" }
JSON.stringify(x)
-> "{}"

在TypeScript中将字符串转换为枚举

1 个答案: