问题

在vite.config.ts中配置全局替换变量：

define: {
    __DEV__: true
 }

使用：

因为没有声明DEV，所以ts会报错

解决方法

看了一下Vue核心库中是使用了global.d.ts进行全局声明

/// <reference types="vite/client" />
// Global compile-time constants
declare var __DEV__: boolean

然后就解决啦。

vuejs-core中的global.d.ts

/// <reference types="vite/client" />
// Global compile-time constants
declare var __DEV__: boolean
declare var __TEST__: boolean
declare var __BROWSER__: boolean
declare var __GLOBAL__: boolean
declare var __ESM_BUNDLER__: boolean
declare var __ESM_BROWSER__: boolean
declare var __NODE_JS__: boolean
declare var __SSR__: boolean
declare var __COMMIT__: string
declare var __VERSION__: string
declare var __COMPAT__: boolean
// Feature flags
declare var __FEATURE_OPTIONS_API__: boolean
declare var __FEATURE_PROD_DEVTOOLS__: boolean
declare var __FEATURE_SUSPENSE__: boolean
// for tests
declare namespace jest {
  interface Matchers<R, T> {
    toHaveBeenWarned(): R
    toHaveBeenWarnedLast(): R
    toHaveBeenWarnedTimes(n: number): R
  }
}
declare module '*.vue' {}
declare module 'file-saver' {
  export function saveAs(blob: any, name: any): void
}
declare module '@vue/repl' {
  import { ComponentOptions } from '@vue/runtime-core'
  const Repl: ComponentOptions
  const ReplStore: any
  export { Repl, ReplStore }
}
declare interface String {
  /**
   * @deprecated Please use String.prototype.slice instead of String.prototype.substring in the repository.
   */
  substring(start: number, end?: number): string
}