TypeScript的字符串枚举-“类型...不可分配给类型..." [英] TypeScript's string enums - "Type ... is not assignable to type ..."

问题描述

我最近将TypeScript的版本从2.3.4升级到了2.4.0，希望使用

I have recently upgraded the version of TypeScript from 2.3.4 to 2.4.0 hoping to use the string enums. To my dismay, however, I have been greeted with the error messages:

Severity  Code    Description Project File    Line    Suppression State
Error TS2322  Type '"E"' is not assignable to type
'StepType'.   ClientApp (tsconfig
project)  Z:\SMART\Smart\Smart\ClientApp\app\models\process.model.ts  17  Active
Error TS2322  Type '"S"' is not assignable to type
'StepType'.   ClientApp (tsconfig
project)  Z:\SMART\Smart\Smart\ClientApp\app\models\process.model.ts  14  Active
Error TS2322  Type '"A"' is not assignable to type
'StepType'.   ClientApp (tsconfig
project)  Z:\SMART\Smart\Smart\ClientApp\app\models\process.model.ts  15  Active
Error TS2322  Type '"D"' is not assignable to type
'StepType'.   ClientApp (tsconfig
project)  Z:\SMART\Smart\Smart\ClientApp\app\models\process.model.ts  16  Active

错误消息适用于以下代码段(带有行号):

The error messages apply to the following code snippet (with the line numbers):

13. export enum StepType {
14.    Start = 'S',
15.    Activity = 'A',
16.    Decision = 'D',
17.    End = 'E'
18. }

我正在使用Visual Studio 2017，它声称已安装TypeScript 2.4.0:

I am using Visual Studio 2017 which claims TypeScript 2.4.0 is installed:

我搜索了

解决此问题的方法是下载并安装 TypeScript 2.4 SDK ，然后从选项中选择较新的版本:

The way to resolve the issue was to download and install TypeScript 2.4 SDK and then select from the options the newer version:

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