TS的编译环境搭建-webpack和ts-node两种方式
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前言
JavaScript无疑是一门非常优秀的编程语言，也在web端、移动端、小程序端、桌面端以及服务器端被应验着。但是由于历史因素，JavaScript语言本身存在着许多的缺点。比如至今JavaScript也没有加入类型检测这一机制。为了弥补JavaScript类型约束的缺失，很多公司提出了自己的方案，由微软提出的TypeScript(TS)出现在了众人面前。
TS和目前流行的框架结合的就很好，比如Angular、Vue3和React等。
一、初识TS
Github的 的描述是
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
TS的更多知识可以查阅官网
我们可以将TypeScript理解成加强版的JavaScript，TypeScript最终会被编译成JavaScript代码。就像官方说的
- 始于JavaScript，归于JavaScript
- TypeScript是一个强大的工具，用于构建大型项目
- 拥有先进的JavaScript
二、编译环境
TypeScript最终会被编译成JavaScript代码，所以我们需要搭建对应的环境。
要将TS代码编译成JS代码，然后再将JS代码运行在浏览器上。这第一步就需要全局安装TypeScript，通过TypeScript的compiler将代码编译成JS代码。
npm install -g typescript
使用以下命令查看版本
tsc --version
一个简单的例子🌰：
function sum(num1:number,num2:number){
return num1 + num2
}
const total = sum(10,20)
console.log('---total---',total)
export {}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<script src="./index.ts"></script>
<body>
</body>
</html>
在浏览器中打开控制台会发现报错
TS文件不能直接运行在浏览器中，需要编译成JS才行。
在代码所在的目录下运行命令
tsc index.ts
会发现目录下多了一个index.js的文件，将html中的index.ts换成index.js，再去查看控制台
目录是这样的
PS：还有一点需要注意的是须将生成的js文件中关于模块的代码注释
如果要这样编译TS文件就太繁琐了，而且实际开发中，一个项目不止一个TS文件。所以我们不会这样编译TS代码的。实际上，我们可以通过两种不同的方式达到简化编译的效果。 方式一，通过webpack配置TS的编译环境； 方式二，通过ts-node库为TS的运行提供环境。 我们先来看第二种，操作比较简单点，然后重点说说第一种。
2.1 ts-node配置TS运行环境
首先需要安装ts-node
npm install ts-node -g
还需要安装相关的依赖tslib和@types/node
npm install tslib @types/node -g
然后，就可以通过ts-node来运行TypeScript的代码
ts-node index.ts
一个小例子🌰
2.2 webpack搭建TS环境
一般项目的开发都会使用npm来管理项目的依赖，而且webpack本身也有许多的依赖。所以我们先初始化package.json文件 npm init -y
然后是安装相关依赖
首先是安装TypeScript
npm install typescript
之前已经全局安装过typescript，为什么还需要本地安装呢？ 因为webpack会在本地查找TypeScript的依赖。
需要tsconfig.json配置文件，针对Typscript的相关配置。通过命令生成文件
tsc --init
生成的tsconfig.json文件
{
"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', 'ES2021', 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', 'react', 'react-jsx' or 'react-jsxdev'. */
// "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. */
// "noUncheckedIndexedAccess": true, /* Include 'undefined' in index signature results */
// "noImplicitOverride": true, /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
// "noPropertyAccessFromIndexSignature": true, /* Require undeclared properties from index signatures to use element accesses. */
/* 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. */
}
}
npm install ts-loader
ts-loader用来解析ts文件，后面用在webapck配置文件中
然后是配置webpack的相关内容
安装webpack及相关依赖
npm install webpack webpack-cli -D
npm install webpack-dev-server html-webpack-plugin -D
需要webpack-dev-server来开启服务，html-webpack-plugin的作用是编译后的代码放在html中，用这个插件来配置 template 模板。
完整的webpack配置：
const path = require("path")
const HtmlWebpackPlugin = require("html-webpack-plugin")
module.exports = {
mode: "development",
entry: "./src/index.ts",
output:{
path: path.resolve(__dirname,"./dist"),
filename: 'bundle.js'
},
resolve:{
extensions:['.js','.ts','.cjs','.json']
},
devServer:{},
module:{
rules:[
{
test:/\.ts$/,
loader:'ts-loader'
},
{
test:/\.(png|jpe?g|svg|gif)$/,
type: 'asset/resource'
}
]
},
plugins:[
new HtmlWebpackPlugin({
template: './index.html'
})
]
}
代码的运行和打包命令在 package.json 的 script 中
{
"name": "ts-webpack",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"serve": "webpack serve",
"build": "webpack"
},
"keywords": [],
"author": "",
"license": "ISC",
"dependencies": {
"typescript": "^5.3.3"
},
"devDependencies": {
"html-webpack-plugin": "^5.6.0",
"ts-loader": "^9.5.1",
"webpack": "^5.89.0",
"webpack-cli": "^5.1.4",
"webpack-dev-server": "^4.15.1"
}
}
引入图片时需要注意，要写一个类型声明文件，以.d.ts结尾，
// 声明模块
declare module "*.jpeg"
declare module "*.jpg"
declare module "*.png"
declare module "*.svg"
//不加声明文件的话，这里引入会报错
//Cannot find module './img/icon.jpeg' or its corresponding type declarations.
import iconImg from "./img/icon.jpeg"
import { sum } from "./utils/math"
let message = 'Hello TypeScript'
// message = 8888
console.log('---message---',message)
const total = sum(10,20)
console.log('---total---',total)
const imgEl = document.createElement('img')
imgEl.src = iconImg
document.body.append(imgEl)
目录结构：
运行效果：
