背景
最近一直在重构react项目，由于项目历史原因，将之前parcel打包工具换成了webpack，并选择了使用create-react-app作为项目开发脚手架。
接着就是把项目中flow类型检查工具移除掉了，替换成typescript。
相关文档
让项目支持ts的两种方式
- 使用typescript创建react-app项目
yarn create react-app my-app --typescript
- 要将 TypeScript 添加到 Create React App 项目
yarn add typescript @types/node @types/react @types/react-dom @types/jest
在Create React App项目中添加支持ts
- 安装typescript及声明类型
yarn add typescript @types/react @types/react-dom @types/node @types/jest
- 配置tsconfig.json
{
"compilerOptions": {
"target": "es5",// 目标语言的版本
"lib": ["dom", "dom.iterable", "es2015.promise", "esnext"],
// 编译时引入的 ES 功能库，包括：es5 、es6、es7、dom 等。// 如果未设置，则默认为： target 为 es5 时: ["dom", "es5", "scripthost"]
//target 为 es6 时: ["dom", "es6", "dom.iterable", "scripthost"]
"allowJs": true, // 允许编译器编译JS，JSX文件
"checkJs": true, // 允许在JS文件中报错，通常与allowJS一起使用
"skipLibCheck": true,
"esModuleInterop": true,// 允许export=导出，由import from 导入
"allowSyntheticDefaultImports": true,
"strict": true,// 开启所有严格的类型检查
"forceConsistentCasingInFileNames": true,
"module": "esnext",// 生成代码的模板标准
"moduleResolution": "node",// 模块解析策略，ts默认用node的解析策略，即相对的方式导入
"resolveJsonModule": true,
"isolatedModules": true,
"noEmit": true,// 不输出文件,即编译后不会生成任何js文件
"jsx": "react",//在 .tsx 中支持 JSX ：React 或 Preserve
"strictFunctionTypes": false,// 不允许函数参数双向协变
"downlevelIteration": true,// 降级遍历器实现，如果目标源是es3/5，那么遍历器会有降级的实现
"noFallthroughCasesInSwitch": true,// 防止switch语句贯穿(即如果没有break语句后面不会执行)
"baseUrl": "./src" // 解析非相对模块的基地址，默认是当前目录
},
"include": ["src", "**/*.ts", "**/*.tsx"],
"exclude": ["./node_modules"]
}
这里需要注意的是，现有项目由于都是js文件，所有我们需要开启allowJs为true支持编译js文件，让之前的项目可以正常跑起来，
然后再慢慢的将之前的js代码改造成ts代码。
这里再说一下关于jsx、tsx和ts的区别
- JSX，是一个 JavaScript 的语法扩展，在React框架中开始流行-
- tsx，如要在typescript中使用jsx语法，则扩展名命名文件使用.tsx后缀
- ts，typescript默认使用.ts扩展名
- 创建Content.tsx文件和content.ts文件
//Content.tsx
import React from ‘react‘
import { user } from ‘./content‘
const Content: React.FC = () => {
const { name } = user
return (
<div>
hi,{name}
</div>
)
}
export default Content
//content.ts
interface User {
name: string
}
export const user: User = {
name: ‘Kerry‘
}
其他
上面的tsconfig.json文件我们也可以通过命令的方式进行创建
tsc --init
这里如果报错command not found: tsc，需要使用全局方式安装typescript yarn global add typescript
执行以上命令后，会为我们再根目录下生成一个默认的tsconfig.json文件
- compilerOptions 用来配置编译选项
- include 指定编译目录
- exclude 排除的编译的目录
更多配置可以查看https://www.typescriptlang.org/docs/handbook/tsconfig-json.html
{
"compilerOptions": {
/* Visit https://aka.ms/tsconfig.json to read more about this file */
/* Basic Options */
// "incremental": true, /* Enable incremental compilation */
"target": "es5", /* Specify ECMAScript target version: ‘ES3‘ (default), ‘ES5‘, ‘ES2015‘, ‘ES2016‘, ‘ES2017‘, ‘ES2018‘, ‘ES2019‘, ‘ES2020‘, or ‘ESNEXT‘. */
"module": "commonjs", /* Specify module code generation: ‘none‘, ‘commonjs‘, ‘amd‘, ‘system‘, ‘umd‘, ‘es2015‘, ‘es2020‘, or ‘ESNext‘. */
// "lib": [], /* Specify library files to be included in the compilation. */
// "allowJs": true, /* Allow javascript files to be compiled. */
// "checkJs": true, /* Report errors in .js files. */
// "jsx": "preserve", /* Specify JSX code generation: ‘preserve‘, ‘react-native‘, or ‘react‘. */
// "declaration": true, /* Generates corresponding ‘.d.ts‘ file. */
// "declarationMap": true, /* Generates a sourcemap for each corresponding ‘.d.ts‘ file. */
// "sourceMap": true, /* Generates corresponding ‘.map‘ file. */
// "outFile": "./", /* Concatenate and emit output to single file. */
// "outDir": "./", /* Redirect output structure to the directory. */
// "rootDir": "./", /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
// "composite": true, /* Enable project compilation */
// "tsBuildInfoFile": "./", /* Specify file to store incremental compilation information */
// "removeComments": true, /* Do not emit comments to output. */
// "noEmit": true, /* Do not emit outputs. */
// "importHelpers": true, /* Import emit helpers from ‘tslib‘. */
// "downlevelIteration": true, /* Provide full support for iterables in ‘for-of‘, spread, and destructuring when targeting ‘ES5‘ or ‘ES3‘. */
// "isolatedModules": true, /* Transpile each file as a separate module (similar to ‘ts.transpileModule‘). */
/* Strict Type-Checking Options */
"strict": true, /* Enable all strict type-checking options. */
// "noImplicitAny": true, /* Raise error on expressions and declarations with an implied ‘any‘ type. */
// "strictNullChecks": true, /* Enable strict null checks. */
// "strictFunctionTypes": true, /* Enable strict checking of function types. */
// "strictBindCallApply": true, /* Enable strict ‘bind‘, ‘call‘, and ‘apply‘ methods on functions. */
// "strictPropertyInitialization": true, /* Enable strict checking of property initialization in classes. */
// "noImplicitThis": true, /* Raise error on ‘this‘ expressions with an implied ‘any‘ type. */
// "alwaysStrict": true, /* Parse in strict mode and emit "use strict" for each source file. */
/* Additional Checks */
// "noUnusedLocals": true, /* Report errors on unused locals. */
// "noUnusedParameters": true, /* Report errors on unused parameters. */
// "noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
// "noFallthroughCasesInSwitch": true, /* Report errors for fallthrough cases in switch statement. */
/* Module Resolution Options */
// "moduleResolution": "node", /* Specify module resolution strategy: ‘node‘ (Node.js) or ‘classic‘ (TypeScript pre-1.6). */
// "baseUrl": "./", /* Base directory to resolve non-absolute module names. */
// "paths": {}, /* A series of entries which re-map imports to lookup locations relative to the ‘baseUrl‘. */
// "rootDirs": [], /* List of root folders whose combined content represents the structure of the project at runtime. */
// "typeRoots": [], /* List of folders to include type definitions from. */
// "types": [], /* Type declaration files to be included in compilation. */
// "allowSyntheticDefaultImports": true, /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
"esModuleInterop": true, /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies ‘allowSyntheticDefaultImports‘. */
// "preserveSymlinks": true, /* Do not resolve the real path of symlinks. */
// "allowUmdGlobalAccess": true, /* Allow accessing UMD globals from modules. */
/* Source Map Options */
// "sourceRoot": "", /* Specify the location where debugger should locate TypeScript files instead of source locations. */
// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSourceMap": true, /* Emit a single file with source maps instead of having a separate file. */
// "inlineSources": true, /* Emit the source alongside the sourcemaps within a single file; requires ‘--inlineSourceMap‘ or ‘--sourceMap‘ to be set. */
/* Experimental Options */
// "experimentalDecorators": true, /* Enables experimental support for ES7 decorators. */
// "emitDecoratorMetadata": true, /* Enables experimental support for emitting type metadata for decorators. */
/* Advanced Options */
"skipLibCheck": true, /* Skip type checking of declaration files. */
"forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */
}
}