基于 TypeScript 开发 NPM 模块

初始化 NPM 项目

mkdir project-name
cd project-name
npm init

添加开发基础包

添加 TypeScript

yarn add typescript -D

添加 Jest 测试工具

yarn add jest ts-jest @types/jest -D

添加 @types/node

yarn add @types/node -D

初始化 TypeScript 配置

./node_modules/.bin/tsc --init

这会在你的项目根目录新建一个 tsconfig.json 文件

现在的目录结构如下：

.
├── node_modules
├── package.json
├── tsconfig.json
└── yarn.lock

文件解析

tsconfig.json

这是 TypeScript 的配置文件，默认仅启用了几项，我一般的配置如下：

{
  "compilerOptions": {
    /* Basic Options */
    "target": "es5" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */,
    "module": "commonjs" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */,
    "lib": [
      "es6"
    ] /* 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 */
    // "incremental": true,                   /* Enable incremental 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. */

    /* 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. */
  },
  "include": ["./src/**/*"],
  "exclude": ["node_modules", "src/__tests__"]
}

package.json

添加了几条 scripts：

{
  "name": "project-name",
  "version": "0.0.0-development",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "rm -rf ./dist && tsc",
    "watch": "yarn test --watch",
    "setup": "yarn install && npx npm-install-peers",
    "test": "jest"
  },
  "author": "",
  "license": "SEE LICENSE IN LICENSE FILE",
  "devDependencies": {
    "@types/jest": "^24.0.13",
    "@types/node": "^12.0.3",
    "jest": "^24.8.0",
    "ts-jest": "^24.0.2",
    "typescript": "^3.4.5"
  }
}

添加 jest.config.js 文件

内容如下：

module.exports = {
  // We always recommend having all TypeScript files in a src folder in your project. We assume this is true and specify this using the roots option.
  roots: ["<rootDir>/src"],
  transform: {
    "^.+\\.tsx?$": "ts-jest" //The transform config just tells jest to use ts-jest for ts / tsx files.
  }
};

添加 .gitignore 文件

该文件告诉 git 哪些文件不需要跟踪

# Logs
logs
*.log
npm-debug.log*
yarn-debug.log*
yarn-error.log*

# Runtime data
pids
*.pid
*.seed
*.pid.lock

# Directory for instrumented libs generated by jscoverage/JSCover
lib-cov

# Coverage directory used by tools like istanbul
coverage

# nyc test coverage
.nyc_output

# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
.grunt

# Bower dependency directory (https://bower.io/)
bower_components

# node-waf configuration
.lock-wscript

# Compiled binary addons (https://nodejs.org/api/addons.html)
build/Release

# Dependency directories
node_modules/
jspm_packages/

# TypeScript v1 declaration files
typings/

# Optional npm cache directory
.npm

# Optional eslint cache
.eslintcache

# Optional REPL history
.node_repl_history

# Output of 'npm pack'
*.tgz

# Yarn Integrity file
.yarn-integrity

# dotenv environment variables file
.env

# next.js build output
.next

# map
*.map

# gitbook
_book

初始化 git 项目

git init

jest watch 需要有 git 环境才能运行

添加 src/index.ts 文件

内容如下：

export const sum = (a: number, b: number): number => a + b;

添加 src/__tests__

按我们的 jest 测试用例：src/__tests__/index.test.ts，内容如下：

import { sum } from "..";

test("sum", () => {
  expect(sum(1, 2)).toBe(3);
});

开始开发

yarn jest

此时终端显示如下信息：

 PASS  src/__tests__/index.test.ts
  ✓ sum (15ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        2.133s
Ran all test suites related to changed files.

Watch Usage
 › Press a to run all tests.
 › Press f to run only failed tests.
 › Press p to filter by a filename regex pattern.
 › Press t to filter by a test name regex pattern.
 › Press q to quit watch mode.
 › Press Enter to trigger a test run.

现在修改一下 index.ts，文件内容改为下面这样：

export const sum = (a: number, b: number): number => a + b;

export const multiply = (a: number, b: number): number => a * b;

再修改 __tests__/index.test.ts，内容如下：

import { sum, multiply } from "..";

test("sum", () => {
  expect(sum(1, 2)).toBe(3);
});

test("multiply", () => {
  expect(multiply(2, 3)).toBe(6);
});

会发现终端会自动测试你的代码：

 PASS  src/__tests__/index.test.ts
  ✓ sum (4ms)
  ✓ multiply

Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        4.164s
Ran all test suites related to changed files.

完整的代码可以在下面看到：

• typescript-module-boilerplate