我最近遇到了这个问题，通过在src文件夹中创建一个index.d.ts来覆盖res.locals，成功地解决了这个问题，我的实现如下所示：

// src/index.d.ts
import 'express';

interface Locals {
  message?: string;
}

declare module 'express' {
  export interface Response  {
    locals: Locals;
  }
}

确保您的tsconfig.json中也包含了它，例如

// somewhere in your tsconfig.json
  "include": [
    "src/**/*.ts"
  ]

您可以像平常一样使用该界面

import { Request, Response, NextFunction } from 'express';

export const handler = (req: Request, res: Response, next: NextFunction) => {
  // should be typed
  res.locals.message = 'hello'
}

希望这有帮助！

不幸的是，没有办法使用接口合并来覆盖任何类型。你可以对类型做一些手术，用Map类型和条件类型来替换类型：

import * as express from 'express'

type Omit<T, K extends keyof T> = Pick<T, Exclude<keyof T, K>>

type MyResponse = Omit<express.Response, "locals"> & { 
  locals: {
    myVar: number
  }
}
function middleware(
  req: express.Request, 
  res: MyResponse, 
  next: express.NextFunction
) {
  res.locals.myVar = '10' // error now
  next()
}

当前接受的答案（https://stackoverflow.com/a/57509904/5043802）已过时且已损坏。新的解决方案是将以下内容添加到项目中的*.d.ts文件（包含在tsconfig中）：

// src/index.d.ts
declare global {
  namespace Express {
    interface Locals {
      shopify: { session: Session }
    }
  }
}

有关说明，请访问https://github.com/DefinitelyTyped/DefinitelyTyped/blob/b986359dc0a8a2108b777c3eb7d3d51909408631/types/express-serve-static-core/index.d.ts#L16