【One by one系列】一步步学习TypeScript

function greeter(persion:string){
	return "Hello, "+persion
}
let user=[0,1,2];
greeter(user);//编译错误

//允许我们在实现接口时候只要保证包含了接口要求的结构就可以，而不必明确地使用 implements语句。
interface Person{
    firstName:string;
    lastName:string;
}

function greeter(person: Person) {
    return "Hello, " + person.firstName + " " + person.lastName;
}

let user = { firstName: "Jane", lastName: "User" };
greeter(user);

class Student {
    fullName: string;
    constructor(public firstName, public middleInitial, public lastName) {
        this.fullName = firstName + " " + middleInitial + " " + lastName;
    }
}

interface Person {
    firstName: string;
    lastName: string;
}

function greeter(person : Person) {
    return "Hello, " + person.firstName + " " + person.lastName;
}

let user = new Student("Jane", "M.", "User");

greeter(user);

//a.ts
function hide(){
	$('#content').hide();//报错
}
//这里ts会报错，TypeScript不知道$是什么，换句话说，Ts不认识美元符号，所以需要有一个文件来告诉typescript，$是要调用jquery，---这个文件就是类型定义文件

{
    "compilerOptions": {
        "module": "system",//指定生成哪个模块系统代码： "None"， "CommonJS"， "AMD"， "System"， "UMD"， "ES6"或 "ES2015"。【ps】只有 "AMD"和 "System"能和 --outFile一起使用。【ps】"ES6"和 "ES2015"可使用在目标输出为 "ES5"或更低的情况下。
        "noImplicitAny": true,//在表达式和声明上有隐含的 any类型时报错。
        "removeComments": true,//删除所有注释，除了以 /!*开头的版权信息。
        "preserveConstEnums": true,//保留 const和 enum声明。
        "outFile": "../../built/local/tsc.js",//将输出文件合并为一个文件。合并的顺序是根据传入编译器的文件顺序和 ///<reference``>和 import的文件顺序决定的。查看输出文件顺序文件了解详情。
        "sourceMap": true//生成相应的 .map文件。
    },
    "files": [
        "core.ts",
        "sys.ts",
        "types.ts",
        "scanner.ts",
        "parser.ts",
        "utilities.ts",
        "binder.ts",
        "checker.ts",
        "emitter.ts",
        "program.ts",
        "commandLineParser.ts",
        "tsc.ts",
        "diagnosticInformationMap.generated.ts"
    ],//项目中不需要
    "include": [
        "src/**/*"
    ],
    "exclude": [
        "node_modules",
        "**/*.spec.ts"
    ]
}

{
  "compilerOptions": {
    /* Basic Options */
    // "incremental": true,                   /* Enable incremental compilation */
    "target": "es6",                          /* 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": "./dist",                        /* Redirect output structure to the directory. */
     "rootDir": "./src",                       /* 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 */
    "forceConsistentCasingInFileNames": true  /* Disallow inconsistently-cased references to the same file. */
  }
}

npm init -y #package.json

cnpm i express #express 包

cnpm i -D typescript ts-node nodemon @types/node @types/express 

{
  "name": "ts-demo",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "node dist/index.js", //启动服务
    "dev":"nodemon src/index.ts",//监听文件变化 
    "build":"tsc -p ."//编译文件
  },//主要修改在这里
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "jquery": "^3.4.1"
  },
  "devDependencies": {
    "@types/express": "^4.17.2",
    "@types/node": "^13.7.6",
    "nodemon": "^2.0.2",
    "ts-node": "^8.6.2",
    "typescript": "^3.8.2"
  }
}

//es6写法
// import express from "express";

// const app= express();

// app.get('/',(req,res)=>{
//     res.send("hello,I'm Carfield")
// })
// app.listen(5000,()=>{
//     console.log('Server running,port:5000...');
// })


//ts写法，明显的类型注解,改改参数 感受下ts带来的好处
import express,{Application,Request,Response,NextFunction  } from "express";


const add=(a:number,b:number):number=>a+b

const app:Application=express();
app.get('/',(req:Request,res:Response,next:NextFunction)=>{
    console.log(add(5,5));   
    res.send("hello,I'm Carfield")
})
app.listen(5000,()=>{
    console.log('Server running,port:5000...');
})

....
TSError: ⨯ Unable to compile TypeScript:
src/index.ts:22:23 - error TS2345: Argument of type '"5"' is not assignable to parameter of type 'number'.

22     console.log(add(5,'5'));

Server running,port:5000...