Typescript 如何获得一个免费的'；aString'；值匹配一个literal'；aString'；类型？

在将项目转换为TypeScript时，我遇到了以下问题

当我将

作为“http”删除时

在此处强制转换：

我在这里得到一个错误：

“http”字符串似乎未被识别为“http”类型？！ 通过使用以下命令

npminit@whook

运行项目副本，您可以轻松地实时检查问题

错误：

Argument of type '{ openapi: string; info: { version: string; title: any; description: any; }; servers: { url: string; }[]; components: { securitySchemes: { fakeAuth: { type: "apiKey"; description: string; name: string; in: string; }; bearerAuth: { ...; }; } | { ...; }; }; paths: any; }' is not assignable to parameter of type 'Document'.
  Types of property 'components' are incompatible.
    Type '{ securitySchemes: { fakeAuth: { type: "apiKey"; description: string; name: string; in: string; }; bearerAuth: { type: string; description: string; scheme: string; }; } | { bearerAuth: { type: string; description: string; scheme: string; }; }; }' is not assignable to type 'ComponentsObject'.
      Types of property 'securitySchemes' are incompatible.
        Type '{ fakeAuth: { type: "apiKey"; description: string; name: string; in: string; }; bearerAuth: { type: string; description: string; scheme: string; }; } | { bearerAuth: { type: string; description: string; scheme: string; }; }' is not assignable to type '{ [key: string]: ReferenceObject | HttpSecurityScheme | ApiKeySecurityScheme | OAuth2SecurityScheme | OpenIdSecurityScheme; }'.
          Type '{ fakeAuth: { type: "apiKey"; description: string; name: string; in: string; }; bearerAuth: { type: string; description: string; scheme: string; }; }' is not assignable to type '{ [key: string]: ReferenceObject | HttpSecurityScheme | ApiKeySecurityScheme | OAuth2SecurityScheme | OpenIdSecurityScheme; }'.
            Property 'bearerAuth' is incompatible with index signature.
              Type '{ type: string; description: string; scheme: string; }' is not assignable to type 'ReferenceObject | HttpSecurityScheme | ApiKeySecurityScheme | OAuth2SecurityScheme | OpenIdSecurityScheme'.
                Type '{ type: string; description: string; scheme: string; }' is not assignable to type 'HttpSecurityScheme'.
                  Types of property 'type' are incompatible.
                    Type 'string' is not assignable to type '"http"'.ts(2345)

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显式变量类型修复了没有（错误）强制转换的编译错误：

从“openapi类型”导入{OpenAPIV3}；
const API:OpenAPIV3.Document={
// ...
键入：“http”，
// ...
};

看起来类型推断确实有问题。同时验证您的答案，但希望得到更详细的答案，说明原因。@nfroidure typescript不会将文字类型保留太长时间，尤其是在声明对象时。所以它将被提升为一个字符串。但是，在声明变量时传递确切的类型注释将约束字段为特定类型（如示例中的文字类型）。