跟着Vam一起学习Typescript（第一期）

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

    1

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

作者：Vam的金豆之路

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