跟着Vam一起学习Typescript（第一期）(更新中)

布满荆棘的人生 2021-08-26 14:23 291阅读 0赞

## 一、安装环境与配置 ##

#### 1、命令行安装 ####

npm i -g typescript

#### 2、快捷打开Vs Code编辑器 ####

创建一个项目文件夹，在该文件夹下打开命令行工具，使用`code .`命令快速打开编辑器（如果计算机提示没有这个命令，请查找到编辑器安装目录`bin`文件夹下，复制地址。到系统的环境变量下Path，编辑，在前面加上`;`，粘贴进去就好了）。

#### 3、运行typesript以及同步typesript与js转换 ####

我们在项目文件夹下创建一个名叫`demo1.ts`文件。这就是我们学习`typesript`的起点，要记住`typesript`需要转换成`js`文件才可以被浏览器识别，所以需要运行命令：

tsc demo1.ts

这样就会在文件夹下生成一个名叫`demo1.js`文件。是不是感觉每次写完都要运行命令很烦，所以我们推荐使用**Vs code**编辑器，让你每次编写`ts`的时候都会同步编译成`js`文件。教程如下：  
在项目文件夹下运行命令：

tsc --init

项目文件夹下，会生成一个`tsconfig.json`文件。取消注释 `"outDir": "./js",`，这就是输出js文件所要存放的地址，这里我改写了在项目文件夹下的**js文件夹**。

{ 
      "compilerOptions": { 
        /* 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": "./js",                        /* 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 */
        "forceConsistentCasingInFileNames": true  /* Disallow inconsistently-cased references to the same file. */
      }
    }

然后，在**vs code编辑器**上方的**终端选项**找到**运行任务**选项，点击它。有两个选项：  
选择 `tsc:监视-tsconfig.json`。就OK了。

#### 4、安装编辑器支持Typescript插件 ####

这里推荐Vs code的插件： **TypeScript Hero**

## 二、学习Typescript的数据类型 ##

**Typescript**一共有10种数据类型。

*  number类型
 *  string类型
 *  数组类型
 *  元组类型
 *  枚举类型
 *  boolean类型
 *  any类型
 *  null和undefined
 *  void 类型
 *  never 类型

// 1、number类型
    let num:number=1;
    console.log(num); // 1
    // 2、string类型
    let str:string='str';
    console.log(str); // str
    // 3、数组类型
    let arr:number[]=[1,2,3];
    console.log(arr); // [1,2,3]
    
    let arr:string[]=['1','2','3'];
    console.log(arr); // ['1','2','3']
    
    let arr:Array<string>=['1','2','3'];
    console.log(arr);
    // 4、元组类型
    let arrx:[number,string]=[1,'2'];
    console.log(arrx);  // [1,'2']
    // 5、枚举类型
    enum flag { success=1,error=0};
    let s:flag=flag.success;
    console.log(s); //1
    
    enum word { a,b,c};
    let msg:word=word.b;
    console.log(msg); //1
    
    enum word { a,b=2,c};
    let msg:word=word.c;
    console.log(msg); //3