使用打字稿模板将 create-react-app 更新到 4.0 时出错

我要更新react-scripts到下一个版本（4.0.0）这样我就可以使用本指南使用快速刷新功能here https://gist.github.com/iansu/282dbe3d722bd7231fa3224c0f403fa1。但是当重新启动服务器时，脚本不起作用，因为出现以下错误：

$ yarn start
yarn run v1.22.4
$ react-scripts start
E:\Github\Web\so-rank\node_modules\react-scripts\scripts\utils\verifyTypeScriptSetup.js:210
        appTsConfig.compilerOptions[option] = suggested;
                                            ^

TypeError: Cannot add property noFallthroughCasesInSwitch, object is not extensible
    at verifyTypeScriptSetup (E:\Github\Web\so-rank\node_modules\react-scripts\scripts\utils\verifyTypeScriptSetup.js:210:45)
    at Object.<anonymous> (E:\Github\Web\so-rank\node_modules\react-scripts\scripts\start.js:31:1)
    at Module._compile (internal/modules/cjs/loader.js:1138:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)
    at Module.load (internal/modules/cjs/loader.js:986:32)
    at Function.Module._load (internal/modules/cjs/loader.js:879:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47
error Command failed with exit code 1.

这可以通过启用来解决noFallthroughCasesInSwitch选项在你的tsconfig.json。查看讨论here https://github.com/facebook/create-react-app/issues/9429#issuecomment-674994709了解更多信息。

{
  "compilerOptions": {
    "noFallthroughCasesInSwitch": true,
    ...
  },
  ...
}

对于任何好奇的人来说，上述解决方案并没有修复该错误。它只是跳过运行下面的错误代码，如果未提供，该代码会将建议值分配给打字稿编译器选项。这tsconfig.json产生于react-scripts默认情况下没有noFallthroughCasesInSwitch选项。添加该选项无需运行代码。

// Some options when not present in the tsconfig.json will be assigned
// a suggested value which crashes the program
if (suggested != null) {
  if (parsedCompilerOptions[option] === undefined) {
    appTsConfig.compilerOptions[option] = suggested; // error here
    ...
  }
} 

EDIT:

如果脚本因其他选项而崩溃，并且您的堆栈跟踪与我的问题中的堆栈跟踪相同，则您应该检查您的代码中是否缺少以下编译器选项tsconfig.json

These https://github.com/facebook/create-react-app/blob/ed958938f642007645dd5ac3466db36202f8754e/packages/react-scripts/scripts/utils/verifyTypeScriptSetup.js#L116-L160是 Typescript 编译器选项中未指定时的建议值tsconfig.json

const compilerOptions = {
  // These are suggested values and will be set when not present in the
  // tsconfig.json
  target: {
    parsedValue: ts.ScriptTarget.ES5,
    suggested: 'es5',
  },
  lib: { suggested: ['dom', 'dom.iterable', 'esnext'] },
  allowJs: { suggested: true },
  skipLibCheck: { suggested: true },
  esModuleInterop: { suggested: true },
  allowSyntheticDefaultImports: { suggested: true },
  strict: { suggested: true },
  forceConsistentCasingInFileNames: { suggested: true },
  noFallthroughCasesInSwitch: { suggested: true },
  module: {
    parsedValue: ts.ModuleKind.ESNext,
    value: 'esnext',
    reason: 'for import() and import/export',
  },
  moduleResolution: {
    parsedValue: ts.ModuleResolutionKind.NodeJs,
    value: 'node',
    reason: 'to match webpack resolution',
  },
  resolveJsonModule: { value: true, reason: 'to match webpack loader' },
  isolatedModules: { value: true, reason: 'implementation limitation' },
  noEmit: { value: true },
  jsx: {
    parsedValue: ts.JsxEmit.React,
    suggested: 'react',
  },
  paths: { value: undefined, reason: 'aliased imports are not supported' },
};

您需要将这些选项显式添加到您的tsconfig.json因此脚本可以跳过有问题的分支并避免崩溃。