第一篇：使用Typescript開發Nodejs

這是實現IoC系列的第一步，因為是基於TypeScript的，所以首先我們來看一下如何使用TypeScript來開發NodeJs項目

TypeScript已經得到廣泛的應用，一般開發Nodejs后端時都會使用成熟的框架，比如Nestjs，但是一些小工具，就沒有必要使用框架了，但是又想使用typescript開發，網上有很多關於使用typescript來開發Nodejs應用的教程，我這里做下記錄，可能的話會寫給npm包，一條命令生成應用的骨架。

 

一. npm init: 生成應用骨架

npm init

　　會在當前目錄下生成package.json文件

二. 安裝typescript

npm install typescript --save

 三.初始化typescript環境

.\node_modules\.bin\tsc --init

　　生成默認的tsconfig.json文件

四.修改默認的tsconfig.json文件

1. 項目中會使用到一些es6的語法，比如Symbol，所以需要在tsconfig.json的lib中添加ES2015
2. 項目中會使用到console等命令，使用需要在lib中添加dom
3. 默認的tsc編譯文件的輸出是當前路徑，我們修改為dist
4. Debug時需要用到sourcemap,打開sourcemap
5. 項目中還會使用到裝飾器和反射的metadata這個實驗性技術，所以需要打開experimentalDecorators和emitDecoratorMetadata
6. 項目中使用的代碼都是放在src下面，所以在與compilerOptions平級的地方加上include: ["src/**/*"]

{
  "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": ["ES2015", "DOM"],                             /* 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": "dist",                        /* 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. */
    // "noUncheckedIndexedAccess": true,      /* Include 'undefined' in index signature results */

    /* 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. */
  },
  "include": [
    "src/**/*"
  ]
}

五.修改package.json文件

　　1. 添加typescript編譯命令 tsc --watch

　　2. 添加啟動項目的命令 node dist/index.js

{
  "name": "ts-ioc",
  "version": "1.0.0",
  "description": "this is a tool for project to use the IoC and DI",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "tsc": "tsc --watch",
    "start": "node dist/index.js"
  },
  "author": "Jason",
  "license": "ISC",
  "dependencies": {
    "typescript": "^4.1.3"
  }
}

六.啟動項目

　　1. 先在一個窗口中編譯typescript

npm run-script tsc

　　2. 打開另外一個窗口，啟動項目

npm start

至此，簡單的使用typescript來開發nodejs就完成了，還有很多需要優化的地方，比如使用webpack把啟動變成一步，還有debug的步驟。

七.熱更新

　　之前啟動項目需要npm run-script tsc && npm start,並且是沒有熱更新的，即修改完代碼沒有立即重新啟動。

這里使用nodemon這個庫，實現typescript代碼的熱更新。

nodemon -e ts --exec ts-node src/index.ts

這里用到了nodemon和ts-node,所以需要先安裝它們

npm install nodemon --save-dev
npm install ts-node --save-dev

然后更新package.json文件

  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "tsc": "tsc --watch",
    "start": "nodemon -e ts --exec ts-node src/index.ts",
    "webpack": "webpack --config webpack.config.js --watch"
  },

可以看到，使用了 nodemon -e ts --exec ts-node src/index.ts 來啟動命令，-e ts表示這個是監聽ts文件的，也可以寫-e ts,tsx表示監聽ts文件和tsc文件。

--exec表示需要使用ts-node來編譯代碼。

這樣，就可以實現修改代碼后自己重啟了。

 

 下一篇文章會實現一個簡單的IoC container