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
一个俗套的说法是:-
CallStatus.ts
enum Status
{
PENDING_SCHEDULING,
SCHEDULED,
CANCELLED,
COMPLETED,
IN_PROGRESS,
FAILED,
POSTPONED
}
export = Status
Utils.ts
static getEnumString(enum:any, key:any):string
{
return enum[enum[key]];
}
如何使用
Utils.getEnumString(Status, Status.COMPLETED); // = "COMPLETED"
其他回答
我只是声明了一个接口,并使用该类型的变量访问枚举。保持接口和枚举同步实际上很容易,因为如果枚举中有什么变化,TypeScript会报错,就像这样。
typeof EAbFlagEnum类型的参数不可赋值 参数类型为“IAbFlagEnum”。属性“Move”类型缺失 “typeof EAbFlagEnum”。
这种方法的优点是在各种情况下使用enum(接口)不需要类型强制转换,因此支持更多类型的情况,例如switch/case。
// Declare a TypeScript enum using unique string
// (per hack mentioned by zjc0816)
enum EAbFlagEnum {
None = <any> "none",
Select = <any> "sel",
Move = <any> "mov",
Edit = <any> "edit",
Sort = <any> "sort",
Clone = <any> "clone"
}
// Create an interface that shadows the enum
// and asserts that members are a type of any
interface IAbFlagEnum {
None: any;
Select: any;
Move: any;
Edit: any;
Sort: any;
Clone: any;
}
// Export a variable of type interface that points to the enum
export var AbFlagEnum: IAbFlagEnum = EAbFlagEnum;
使用变量,而不是枚举,可以产生所需的结果。
var strVal: string = AbFlagEnum.Edit;
switch (strVal) {
case AbFlagEnum.Edit:
break;
case AbFlagEnum.Move:
break;
case AbFlagEnum.Clone
}
标记是我的另一个需要,所以我创建了一个NPM模块,添加到这个例子中,并包括测试。
https://github.com/djabraham/ts-enum-tools
为什么不直接使用本地方式访问枚举的字符串呢?
enum e {
WHY,
NOT,
USE,
NATIVE
}
e[e.WHY] // this returns string 'WHY'
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)
TypeScript < 2.4
/** Utility function to create a K:V from a list of strings */
function strEnum<T extends string>(o: Array<T>): {[K in T]: K} {
return o.reduce((res, key) => {
res[key] = key;
return res;
}, Object.create(null));
}
/**
* Sample create a string enum
*/
/** Create a K:V */
const Direction = strEnum([
'North',
'South',
'East',
'West'
])
/** Create a Type */
type Direction = keyof typeof Direction;
/**
* Sample using a string enum
*/
let sample: Direction;
sample = Direction.North; // Okay
sample = 'North'; // Okay
sample = 'AnythingElse'; // ERROR!
从https://basarat.gitbooks.io/typescript/docs/types/literal-types.html
到源代码链接,你可以找到更多更简单的方法来实现字符串文字类型
非常非常简单的Enum string (TypeScript 2.4)
import * from '../mylib'
export enum MESSAGES {
ERROR_CHART_UNKNOWN,
ERROR_2
}
export class Messages {
public static get(id : MESSAGES){
let message = ""
switch (id) {
case MESSAGES.ERROR_CHART_UNKNOWN :
message = "The chart does not exist."
break;
case MESSAGES.ERROR_2 :
message = "example."
break;
}
return message
}
}
function log(messageName:MESSAGES){
console.log(Messages.get(messageName))
}