以下代码可用于在TypeScript中创建enum:
enum e {
hello = 1,
world = 2
};
这些值可以通过以下方式访问:
e.hello;
e.world;
我如何创建一个字符串值enum ?
enum e {
hello = "hello", // error: cannot convert string to e
world = "world" // error
};
以下代码可用于在TypeScript中创建enum:
enum e {
hello = 1,
world = 2
};
这些值可以通过以下方式访问:
e.hello;
e.world;
我如何创建一个字符串值enum ?
enum e {
hello = "hello", // error: cannot convert string to e
world = "world" // error
};
当前回答
打印稿0.9.0.1
enum e{
hello = 1,
somestr = 'world'
};
alert(e[1] + ' ' + e.somestr);
打印稿操场
其他回答
@basarat的回答很棒。下面是一个你可以使用的简化但有点扩展的例子:
export type TMyEnumType = 'value1'|'value2';
export class MyEnumType {
static VALUE1: TMyEnumType = 'value1';
static VALUE2: TMyEnumType = 'value2';
}
console.log(MyEnumType.VALUE1); // 'value1'
const variable = MyEnumType.VALUE2; // it has the string value 'value2'
switch (variable) {
case MyEnumType.VALUE1:
// code...
case MyEnumType.VALUE2:
// code...
}
小js-hack但工作:e[字符串(e.hello)]
如果你想要的主要是易于调试(相当类型检查),不需要为枚举指定特殊值,这是我正在做的:
export type Enum = { [index: number]: string } & { [key: string]: number } | Object;
/**
* inplace update
* */
export function enum_only_string<E extends Enum>(e: E) {
Object.keys(e)
.filter(i => Number.isFinite(+i))
.forEach(i => {
const s = e[i];
e[s] = s;
delete e[i];
});
}
enum AuthType {
phone, email, sms, password
}
enum_only_string(AuthType);
如果您希望支持遗留代码/数据存储,则可以保留数字键。
这样,您就可以避免键入两次值。
最近在使用TypeScript 1.0.1时遇到了这个问题,并以这种方式解决了:
enum IEvents {
/** A click on a product or product link for one or more products. */
CLICK,
/** A view of product details. */
DETAIL,
/** Adding one or more products to a shopping cart. */
ADD,
/** Remove one or more products from a shopping cart. */
REMOVE,
/** Initiating the checkout process for one or more products. */
CHECKOUT,
/** Sending the option value for a given checkout step. */
CHECKOUT_OPTION,
/** The sale of one or more products. */
PURCHASE,
/** The refund of one or more products. */
REFUND,
/** A click on an internal promotion. */
PROMO_CLICK
}
var Events = [
'click',
'detail',
'add',
'remove',
'checkout',
'checkout_option',
'purchase',
'refund',
'promo_click'
];
function stuff(event: IEvents):boolean {
// event can now be only IEvents constants
Events[event]; // event is actually a number that matches the index of the array
}
// stuff('click') won't work, it needs to be called using stuff(IEvents.CLICK)
在最新版本(1.0RC)的TypeScript中,你可以像这样使用枚举:
enum States {
New,
Active,
Disabled
}
// this will show message '0' which is number representation of enum member
alert(States.Active);
// this will show message 'Disabled' as string representation of enum member
alert(States[States.Disabled]);
更新1
要从string value中获取enum成员的number值,你可以使用这个:
var str = "Active";
// this will show message '1'
alert(States[str]);
更新2
在最新的TypeScript 2.4中,引入了字符串enum,如下所示:
enum ActionType {
AddUser = "ADD_USER",
DeleteUser = "DELETE_USER",
RenameUser = "RENAME_USER",
// Aliases
RemoveUser = DeleteUser,
}
有关TypeScript 2.4的更多信息,请阅读MSDN上的博客。