# 01 TypeScript 安装
# 安装
基于node.js安装（前提安装node.js (opens new window)）
npm install -g typescript
# 编译
新建一个helloworld.ts文件，同级目录下命令行执行：
tsc helloworld.ts
完成后就会在同级目录生成同名JS文件helloworld.js。
开发项目级应用每次都tsc进行编译，显然很不方便。下面就需要对项目进行简单配置。
# 开发工具及配置
开发工具：VSCode (opens new window) 同是微软的亲儿子
开始配置：
- 创建
tsconfig.json文件，执行命令：
tsc --init
点击查看配置文件
{
"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": "./", /* 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. */
}
}
我们放开注释outDir设置编译输出目录。
"outDir": "./",编辑输出目录，设置成./会输出到与.ts同级目录下，也方便管理。- 其他命令后面再研究...
- 点击菜单
终端-运行任务输入tsc, 点击tsc:监视-tsconfig.json,就可以自动生成代码了。
# 编译遇到的问题
按照以上第一步生成配置，修改outDir，第二步tsc监视 报如下错误：
> Executing task: tsc -p e:\workspace\typescript\TypeScript-start\examples\tsconfig.json --watch <
tsc : 无法加载文件 D:\Program Files\nodejs\node_modules\node_global\tsc.ps1，因为在此系统上禁止运行脚本。有关详细信息，请参阅 https:/go.mic
rosoft.com/fwlink/?LinkID=135170 中的 about_Execution_Policies。
所在位置 行:1 字符: 1
+ tsc -p e:\workspace\typescript\TypeScript-start\examples\tsconfig.jso ...
+ ~~~
+ CategoryInfo : SecurityError: (:) []，PSSecurityException
+ FullyQualifiedErrorId : UnauthorizedAccess
终端进程已终止，退出代码: 1
终端将被任务重用，按任意键关闭。
原因竟是由于我将VSCode的默认终端改成了Windows PowerShell,改回cmd试试：
> Executing task: tsc -p e:\workspace\typescript\TypeScript-start\examples\tsconfig.json --watch <
[1:03:56] Starting compilation in watch mode...
[1:03:59] Found 0 errors. Watching for file changes.
竟然成功了,同级目录下生成了同名的.js文件。
# 第一个TypeScript应用-Helloworld
创建一个helloworld.html (opens new window)文件，输入html:5回车 快捷生成一个简单页面。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Hello world</title>
</head>
<body>
</body>
</html>
引入.js文件：
<script src="helloworld.js" type="text/javascript"></script>
helloworld.ts (opens new window)
console.log('hello TypeScript!');
var hello:string = 'hello 你好';
document.writeln(hello);
即可看到输出结果,生成对应js文件 (opens new window):
"use strict";
console.log('hello TypeScript!');
var hello = 'hello 你好';
document.writeln(hello);
修改.ts文件，页面也即是响应更新。